[AnemicOak]

Android phones are compatible with Overdrive audiobooks in MP3 format, but not audiobooks in WMA format.

AFAIK the iPhone is the only thing that will handle DRM'd WMA audiobooks (even Windows Phone 7 doesn't support them AFAIK which is weird since WMA is Microsoft's). Note only WMA audiobooks where the publisher allows conversion will work (most will, but not all) and conversion must be done with a Windows PC. You can play them through the iPhone music app or the Audible app (with some success), but AFAIK not the Overdrive app.