The announced departure of Microsoft Chief Software Architect Ray Ozzie is certainly not good news for Microsoft. But his memo to the troops revealed this week could be the best thing that's ever happened to the company.That is, if the troops listen and act on Ozzie's warnings.When I read the long but pointed memo called "Dawn of a New Day" about how Microsoft needs to stop relying on the Windows client OS, I felt relieved that someone from Microsoft finally gets it. Too bad it's a guy who's leaving.Who knows for sure why Ozzie is calling it a day. Maybe he was too soft-spoken or cerebral to fit in with the dog-eat-dog culture at Microsoft or maybe he's leaving on completely amicable terms. Either way, he did spearhead Windows Live, Xbox Live, Office 365 and the Windows Azure cloud platform and I'm sure convinced CEO Steve Ballmer to go "All In" for the cloud. (Ozzie is also well-known for his 2005 memo, "The Internet Services Disruption", warning that online services would threaten Microsoft's business model of selling desktop software. He was right).\nSlideshow: Windows Phone 7: Visual Tour of 10 Upcoming WP7 SmartphonesSlideshow: Seven New Windows 7 Tablets: In PicturesSlideshow: Windows 7 Hardware in Pictures: The Latest and Greatest Laptops\nNow Ozzie is leaving Redmond some pearls of wisdom. If Microsoft doesn't follow through on them, the memo will stand as living proof that at least they were warned.The Ozzie memo also reminded me of my favorite post-Beatles Paul McCartney song, "Listen to What the Man Said". Microsoft soldiers should listen to what this man (Ozzie) said if they want to see Microsoft climb out of its has-been rut and be an innovative company again.The memo is quite lengthy at 3,400 words, but the overarching theme is that the PC is dying and will be replaced by "appliance-like" devices that are connected to always-on services based in the cloud.Ozzie contends that Microsoft is not quite prepared for the post-PC world despite the progress the company has made in the last five years. It has spent too much time protecting its cash cows Windows and Office, while it could have been building the next great smartphone or social network.Some quotes from this week's memo that all Microsoft employees should stick on their office or cubicle walls:"For all our great progress, some of the opportunities I laid out in my memo five years ago remain elusive and are yet to be realized.""Our early and clear vision notwithstanding, our competitors' execution has surpassed our own in mobile experiences, in the seamless fusion of hardware & software & services, and in social networking & myriad new forms of internet-centric social interaction.""The PC-centric\/server-centric model has accreted simply immense complexity\u2026 Complexity sucks the life out of users, developers and IT. Complexity makes products difficult to plan, build, test and use. Complexity introduces security challenges. Complexity causes administrator frustration.""Today's PC's, phones and pads are just the very beginning; we'll see decades to come of incredible innovation from which will emerge all sorts of 'connected companions' that we'll wear, we'll carry, we'll use on our desks & walls and the environment all around us.""The one irrefutable truth is that in any large organization, any transformation that is to 'stick' must emerge from within. Those on the outside can strongly influence, particularly with their wallets. Those above are responsible for developing and articulating a compelling vision, eliminating obstacles, prioritizing resources, and generally setting the stage with a principled approach. But the power and responsibility to truly effect transformation exists in no small part at the edge.""There's one key difference in tomorrow's devices: they're relatively simple and fundamentally appliance-like by design, from birth. They're instantly usable, interchangeable, and trivially replaceable without loss."Does that last one sound like Windows to you?Shane O'Neill covers Microsoft, Windows, Operating Systems, Productivity Apps and Online Services for CIO.com. Follow Shane on Twitter @smoneill. Follow everything from CIO.com on Twitter @CIOonline. Email Shane at email@example.com.