While 1.5 and 1.6 are still alive, Android 2.1 is still a mostly growing OS version (or at least growing in usage due to OEMs updating their handsets). Android 2.2 on the other hand is practically on nothing except the now-defunct Nexus One, so with that out of the way, and every Android manufacturer proclaiming that their handsets will be Froyo’d by this summer, while HTC is planning to have all 2010 handsets updated to this Winter, the latest.
Source: GigaOM, Android Developers
