Android's problem: There's a lot of Androids out there! 1.5, 1.6, 2.0 and 2.1, just to name the major current versions. A problem, 'cause spiffy apps that'll run on 2.0 won't run on 1.5, and now everybody's confused. Google's solution?
To split Android up over the next major versions—Froyo and Gingerbread—carving major features and core elements out of the main OS, so that you can download updates, just like Maps works now, for things like Gmail. It'll even extend to guts-y stuff like input methods, according to Engadget's sources (meaning if Google releases a spiffier new keyboard, you could just download it).
The idea being that if there's an awesome new version of Gmail, you shouldn't be left behind because your carrier or phonemaker isn't on the ball with Android updates, as people languishing with Android 1.5 would tell you. (Just check this month's best Android apps to see how stark the fragmentation is, splintering all kinds of app support.)