[magicalist]

Google wallet is a really poor example of fragmentation that a developer would run into since it has nothing to do with varying hardware and drivers, it's the carriers that are blocking it and (AFAIK) there's no reason that a developer would care whether or not the app itself is there. The hardware is accessible; Verizon and AT&T will use it for their own attempt at a payment system. That whole situation isn't really analogous to any other fragmentation you might encounter.

Android development and testing really isn't all that painful, and most of the new APIs you might miss are backported and available for the more prevalent Gingerbread and now ICS.