Word on the street is when Windows Phone 7 Series launches, Windows Mobile 6.5 will receive a name change to "Windows Phone Classic." Contrary to what you may think, Windows Mobile 6.5 has no plans to leave right after the launch of Windows Phone 7 Series - actually, it'll be staying around for a bit longer. It will, however, only be available to enterprise and emerging markets. The strategy makes sense, given that (1) Microsoft probably wants to get "Windows Mobile" out of everyday vocabulary altogether, and (2) Windows Mobile 6.5 (or whatever you want to call it) will be around and available on several retail devices for quite a while. What's more, since Windows Mobile 6.5 applications are incompatible with Windows Phone 7 Series, it also extends their shelf life a bit.
So for those purchasing Windows Mobile 6.5-equipped devices in the coming months, don't worry - you have a Classic on your hands.