Google need to do something about this although I'm not sure what exactly they can do. The Android userbase is badly fragmented on the core OS version alone. Once you add in the various manufacturer changes which don't need to contributed back to the core then it is even worse.

HTC has their Sense UI layer.
Sony Ericsson has UX which is on their only Android handset and that is stuck with Android 1.6 until the end of the year.
Motorola has MOTOBLUR but their latest handset doesn't use it for some reason.
Samsung appear to be using the stock UI but are awful with releasing updates as most of their phones are stuck with Android 1.5.