Apple surprised the tech world last week by pulling the curtain back on its latest desktop\/laptop operating system: OS X Mountain Lion. The final version will be released this summer, but the developer preview unveiled on Thursday shows that the upcoming OS picks up where OS X 10.7 -- code-named Lion -- left off. The coming update incorporates even more popular features from iOS , the software which runs the iPhone, iPad and iPod touch.The upgrade -- pricing not yet announced -- will be available only as a download from the Mac App Store. Apple won't sell it on disc or on a thumb drive, as it did with earlier versions of OS X. That's a change from past practice and gives Apple another way to showcase its fast-growing App Store.Another change: Apple execs quietly previewed Mountain Lion first with a select few journalists and bloggers. Their early-bird reports last week led to a sudden tsunami of information about Mountain Lion and what it offers: iOS-like Messages, Reminders, Notifications and Game Center, AirPlay Mirroring, and a new security effort called Gatekeeper.It was clear with the release of Lion last year that the Mac OS X and iOS feature sets were morphing; this year, that trend continues with Mountain Lion. The big question for users then becomes whether this melding of features works, whether the iOS-inspired apps and processes fit within the context of a desktop operating system.For better or worse, the future of Apple's desktop OS is full of iOS-esque flourishes, changes that reflect a new Apple way of thinking and indicate where Apple is going.iCloud integrationThe most important element of the new OS is deeper integration with iCloud, the collection of services that stores your data to Apple's servers automatically and then syncs that data across all your devices. On the iPhone and iPad, every photo, document, bookmark, contact -- everything -- gets backed up. And through iCloud, it gets automatically sent to all your Macs\/PCs, iPhones or iPads. To put it another way, iCloud shifts the onus of keeping data organized and up to date on multiple devices from the user to the machine. It's invisible. And it just works.For example, if I see an app I like in the App Store, I can buy it and within a few moments that app is already on my iPhone, my iPads, and my various Macs. When I take a picture on my iPhone, by the time I fire up iPhoto on the Mac, it's already waiting in Photo Stream on all of my devices. iCloud makes living with multiple devices far easier because data is automatically dispensed across them all.Last week, Apple CEO Tim Cook reaffirmed that iCloud is not a strategy with a specific shelf life, but a core part of all future Apple products, just as the Digital Media Hub strategy motivated Apple decisions over last dozen years or so. While iCloud integration on the Mac is not yet as comprehensive as it is in the iDevice lineup, Mountain Lion moves closer to real integration with Apple's online services.The iCloud focus is apparent right away. After downloading and installing Mountain Lion, an iCloud login\/sign up is one of the first things to greet you following a clean install. If you already have an iCloud account, your email, contacts, calendars, FaceTime info, Safari bookmarks and Reading List links are automatically configured. Once the Setup Assistant is complete, a virtual visit to the Mac App Store allows you to easily install any apps you've already bought.With iCloud and a centralized location for app installs, you can be up and running on a new machine with far less effort than before. (More on this in a minute.)More details on iCloudMuch of Mountain Lion's iCloud integration isn't new to Apple products, it's just implemented in a more refined way. For instance, updated applications will feature enhanced Open\/Save options that now include iCloud. This allows documents created on one device to be automatically available on other devices for editing, viewing, or sharing. Before now, you saved documents on your desktop, then had to upload them to the cloud yourself, then go to the other devices and download them yourself.OS X Mountain Lion looks much like its predecessor, Lion, though there's a new desktop wallpaper.In Mountain Lion, the Open\/Save dialogue box sports two options for saving: iCloud or On My Mac. When On My Mac is highlighted, a standard window allows for traditional file system navigation, Spotlight search and all other options you'd expect from a typical OS X Open\/Save prompt. Selecting iCloud, however, replaces the file system window with the iOS linen background and large document icons. (It's similar to Pages on an iOS device.) From the large icon displays, you can flip through multi-page documents, and drag and drop documents onto other icons to create folders, just as you would on the iOS home screen.If no documents are available, you can drag and drop documents to the Open\/Save window to make them accessible via iCloud; they'll be moved from the Mac into iCloud automatically. You can also move documents to iCloud by clicking the little arrow next to a document's title, choosing Move To and selecting iCloud as the location. Just like that, your documents are available to any of your Apple devices with an internet connection.Right now, saving to iCloud or to the Mac is an option, but it looks to me like Apple really hopes to push iCloud saves as the default. I imagine many self-respecting tech geeks will be annoyed by that prospect -- oh, the Geek Rage will flow! -- as this step is yet another in Apple's War on the File System As We Know It. For everybody else, though, this will be a life- and time-saver. Having your documents always available no matter which device you're using, via a user-friendly interface, will be more important than the inability to directly traverse a file-system; if a computer is lost\/stolen\/crashes, documents saved to iCloud will remain secure and safe. Yes, other services like Dropbox already do this, but the tight integration with Mountain Lion will encourage its use, and the 100 million+ users already on iCloud illustrate its potential reach.More iOS bits arriveMountain Lion gets other specific iOS app equivalents that are already designed with iCloud syncing in mind. Specifically, to-do's and reminders have been separated from Mail into the new Reminders application; data entered or removed automatically is transferred across devices. Notes gets a similar treatment; and Messages picks up the iCloud sync, too, implemented in ways that solve the problems inherent with Messages' original siloed nature regarding multiple devices.For instance, do you ever get a message on your phone and wish you could reply from the computer you're on? With Messages, you'll be able to do just that. Messages works on the Mac just as it does on iOS, by using Apple's servers to relay encrypted texts, images, or movies while avoiding SMS rates on mobile devices. Every message is synced across your devices, so you no longer have to be on a specific device for a chat conversation.Already available on iPod touch, iPhone and iPad, Messages replaces iChat on the Mac, and the main chat window sports a chat interface taken directly from the iPad Messages app. The new interface takes up more screen real-estate than iChat, which is annoying, but Messages gains FaceTime integration, which is not. And the fact that all messages are synced across devices is convenient. You can began a conversation on your desktop Mac, then later take part in the same conversation using Siri on an iPhone.The mantra is pretty simple: from any device, to any device.NotificationsiOS 5 brought to Apple's mobile devices the Notification Center. In Mountain Lion, Mac users play a bit of catch-up with the addition of system-wide notifications. As in iOS, notifications slide out from the menu bar as banners that fade away or as dialogue boxes you must interact with to dismiss; unlike iOS, the notifications on the Mac are justified to the right of the screen. A notification banner will appear for five seconds before sliding off of the screen, exit stage right. The Notification menu icon now resides where the Spotlight icon used to be; Spotlight moves a space to the left in the menubar.Pressing the Notification button causes the desktop and on-screen windows to shift to the left, revealing the Notification Center. Notifications appear as a list organized by application on the gray linen background made familiar by iOS, and the notification menu icon has a blue in the center when there are new alerts.The Notifications window slides out from the right side of the screen.Other than that menu icon, which is unique to Mountain Lion, the entire interface is lifted pretty much wholesale from iOS. The interesting bit is that the interactive elements of Notification Center in OS X feels better on the Mac than on smaller screen devices. Why? Because the elements in Notification Center are perfectly sized for mouse clicks; sometimes it takes me a couple of taps to engage the same widgets in Notification Center on an iOS device.One thing I'd love to see added to Notification Center would be a section to track downloads and file transfers. Ever since Mac OS X supported Spaces and multiple desktops, locating the Finder's progress bar is sometimes difficult for me; Notification Center looks like the perfect location to consolidate those types of activities.AirPlay mirroringOne of my all-time favorite iOS features finally makes it as a system-wide service to the Mac: AirPlay Mirroring. AirPlay allows any iOS device to broadcast video, audio or both to an AppleTV-equipped HDTV. On iOS devices, videos, games, music, pictures, presentations, podcasts, apps -- literally, anything -- can be broadcast to an AppleTV, wirelessly, at 720p resolution and 5.1 surround sound, at the push of a button with no configuration.While AirPlay was limited to iTunes in previous versions of OS X, Mountain Lion adds AppleTV support in the Displays system preference. Like iOS, one can configure the AirPlay icon to appear when an AppleTV is located on the same network; and like iOS, the Mac will be able to mirror everything on screen (including audio).Why is this a big deal now that this function is accessible outside of iTunes? Much has been written about Apple working out content deals with networks\/cable providers\/content creators to have content available on the iTunes store. But with AirPlay, that's no longer necessary. Most cable companies and networks now offer their shows online -- think HBO Go, Hulu, etc. -- and with AirPlay, you just call up whatever you want to watch on your computer, when you want it, and watch it on your TV via AirPlay. No content deals are necessary, no new TV is needed, and the whole ecosystem circumvents the current cable provider setup -- the sole exception being the need for broadband.AirPlay in Mountain Lion could cause major disruptions down the line for several industries.GatekeeperOne of the more publicized changes in Mountain Lion is a new paradigm in which the operating system handles security, specifically regarding applications. Currently, OS X can install and run any application from anywhere; a warning pops up the first time an app is launched but that's all that stands in the way of that app running.With the Mac user base growing, so, too, is the danger of malware. Granted, Mac Trojans and viruses are still a tiny blip compared to the malware written for Windows machines on a daily basis, but it's good to see Apple being forward-looking in its attempts to bolster system security, even if it means greater reliance on the Mac App Store. The App Store for OS X works like the iOS app store: curated, Apple-approved apps make it a safe place to purchase software without having to worry about malware.Now comes Gatekeeper . Briefly, Gatekeeper is a new security paradigm in which one of three types of security modes are implemented. The first mode allows applications downloaded from anywhere to run -- it's an option literally called Anywhere in the "Allow applications downloaded from:" section of the Security Preference. This will let the Mac behave as it does now, with app installations from any source allowed with the proper permissions, at the user's discretion.The second option allows for apps to be installed if they come the "Mac App Store and identified developers." This option allows digitally signed apps to run on your Mac. A digitally signed app gives Apple the right to revoke privileges for troublesome apps and track down responsible parties, as each signature is unique to developers. Applications that aren't signed won't be able to run when this mode is enabled.The last option only allows apps downloaded from the Mac App Store to install or run. That's as self-explanatory, and as secure, as you can get.Despite concerns from some that Gatekeeper goes to far, or doesn't go far enough, I like the options. They're a useful compromise for IT departments already accustomed to dealing with malware on the Windows side; once apps necessary to business become "Gatekeeper aware," so to speak, concerns about Mac malware or untrusted apps will be one of the last things on the mind of IT staffers. Granted, it will take some time for app makers to climb on board, but Gatekeeper should start that movement.Mountain Lion's Security & Privacy preference pane now includes Gatekeeper, which is designed to head off malware by setting limits on which apps can run.Share Sheets arriveApple has made social sharing in Mountain Lion more integrated with Share Sheets, which are built in to home-grown applications like QuickTime, Safari and Notes and allow you to easily share what you're looking at with others. (Third-party developers will need to rewrite their apps to incorporate the feature, but its usefulness should be readily apparent, especially for Twitter users.)Every app's Share Sheet has a different set of functions, depending on context. For instance, clicking on Safari's Share Sheet button allows you to add a Web page to the Reading List, to your Bookmarks, or to share it via email, message or tweet. Interestingly enough, Facebook isn't an option in most apps. You won't find Facebook under the System Preference for Mail, Contacts & Calendars (where you will find Twitter). But if you look under the Share menu in a QuickTime window, you can share your movie to FaceBook. The same is true in iPhoto's Share Sheet.Given the explosion in social media, it's a smart move to incorporate easy ways to share digital content. I'd expect to see more of this as OS X develops.Odds and EndsGame Center: Apple has also added Game Center to Mountain Lion. Game Center is a centralized location that on iOS devices provides easy access to global game score and leader-board tracking; it also allows you to see what games friends are playing and how well they're doing, among other details. Game Center's support for turn-based and head-to-head games now comes to the Mac, allowing you to play supported games on your Mac against people playing on iOS devices.Notes: In Lion and earlier versions of OS X, the Notes app was always bound to Mail; but in iOS, Notes has been a standalone app. When Mountain Lion is released, Notes will become a standalone application with an interface lifted from the landscape view on the iPad. (Similarly, to-do's and reminders get the standalone app treatment, too, with their appearance drawn from the iPad.)Safari: Apple's Web browser gets a few tweaks, too, including a new address bar that handles searches as well as url addresses. Safari also gains a "Do Not Track" option, Apple's response to growing privacy concerns among online surfers.Software Update: In Mountain Lion, software updates are now handled through the Mac App Store, and Notifications appear when updates are available for either the operating system or apps downloaded from the Mac App Store. This will surely raise awareness of the App Store and the apps it offers.Final thoughtsLike Lion before it, Mountain Lion continues the merger of iOS and OS X features in a way that helps provide a consistent experience across Apple devices. In concert with iCloud, Apple is moving to make things easy to use no matter which device you have in hand, an iPhone or a iMac, an iPad or a MacBook Air. The main difference revolves around each device's interaction method: mouse and trackpad for the Mac; touch screen gestures on the iPad and iPhone.There's been a lot of talk about whether OS X and iOS are becoming one. Clearly, they overlap and share features, but they're not the same, nor should they be. Apple won't follow the path Microsoft is taking with Windows 8 and its new Metro interface. Sure, Apple will continue to migrate features between iOS and OS X on a case-by-case basis, cherry-picking features that logically work across devices, regardless of the underlying OS. (I wouldn't be surprised to see Siri -- the voice activated assistant that's been such a hit on the iPhone 4S -- show up one day in OS X.)What Apple is doing is creating a consistent ecosystem for your digital world, from media creation to distribution to viewing and sharing. Start something on one device, finish it on another, whether you're writing a document, sharing a link, listening to music or making a video. That's what makes iCloud increasingly important. It takes OS X where computing really needs to go: toward a world of unified data and interface consistency.Notes is now a standalone app and is no longer built into the Mail program.Michael deAgonia , a frequent contributor to Computerworld, is a writer, computer consultant and technology geek who has been working on computers since 1993. You can find him on Twitter ( @mdeagonia ).Read more about mac os in Computerworld's Mac OS Topic Center.