Microsoft's fight to stay in the smartphone game will begin on Oct. 6 when the first so-called "Windows phones" will be made available at retail stores worldwide. The new phones will run Windows Mobile 6.5 and will be available through carriers AT&T, Sprint and Verizon. A few of the confirmed hardware makers that will be running Windows Mobile 6.5 are HTC, HP, LG, Samsung, Toshiba and Sony Ericsson.\n \nMicrosoft promo for Windows Mobile 6.5 and Windows phones.Although Microsoft is promoting Windows Mobile 6.5 as an important turning point in its mobile strategy with a redesigned user interface, improved mobile Web browsing with Internet Explorer and a new applications store, 6.5 is largely viewed as a stepping stone to what Microsoft has called its fully-formed mobile OS, Windows Mobile 7, which is not due until the fourth quarter of 2010. Microsoft has also been criticized for taking too long to develop Windows Mobile 6.5 while it has fallen far behind competitors such as the iPhone, BlackBerry, Android and Palm Pre. In both the consumer and enterprises spaces, Windows Mobile will be like the new kid in school come Oct. 6.Yet despite being perceived as an interim OS, Windows Mobile 6.5's arrival could provide momentum for Microsoft. It will capitalize on the powerful marketing might of the Windows brand in the same month that highly-anticipated client OS Windows 7 is shipping (Oct. 22).WinMo 6.5 also includes two new services: Windows Marketplace for Mobile, a store for mobile apps, and Microsoft My Phone, a service that backs up contacts, calendars, text messages and photos to a PC. The free My Phone service also includes a "Find My Phone" feature that helps users locate a phone that has been lost or stolen. The iPhone has a similar paid service. A lot will be riding on the Windows Mobile app store, as it will inevitably be compared to the iPhone's enormous iTunes App Store and the BlackBerry App World Store. Because Windows Mobile has been around for years, there are thousands of compatible apps floating round the Web, but they are hard to find and have not been consolidated in one place. Marketplace has been designed to be home base for all these disparate apps. Click here to read about what Windows Mobile means for mobile app developers.Microsoft has not commented on how many apps have been approved, though in a CNET article, Stephanie Ferguson, general manager in the Windows Mobile group, said that Netflix, Facebook and a variety of gaming apps will be in Windows Marketplace for Mobile.But not matter how you slice it, Windows Mobile 6.5 faces an uphill climb. Not only is it late to a crowded market, but it's being viewed as a stand in for a newer version (WinMo 7) that doesn't arrive for another year. The climb begins Oct. 6. Are you a Tweeter? Follow me on Twitter at twitter.com\/smoneill. Follow everything from CIO.com on Twitter at twitter.com\/CIOonline.