fragmentation on the official Android Developers Blog, basically saying it doesn't exist. Actually, the language is a little more colorful:
Sure, as Android goes, the term "fragmentation" has meant moderately different things in different contexts over the past couple years -- fair enough. But the fact remains that releasing six major revisions of any platform within the span of 19 months (four of which are in heavy user circulation) is unprecedented and potentially unsettling to manufacturers and consumers alike. Your average Joe isn't going to understand why, for example, his HTC Hero that he bought a few months back can't use the Buzz widget or some of the cooler features in Google Maps, and Google hasn't done a very good job of explaining or justifying it, other than by blocking incompatible apps and updates from being visible in the Market."Because it means everything, it actually means nothing, so the term is useless. Stories on 'fragmentation' are dramatic and they drive traffic to pundits' blogs, but they have little to do with reality. 'Fragmentation' is a bogeyman, a red herring, a story you tell to frighten junior developers. Yawn."