This doesn't solve fragmentation at all. The problem is (from an app developer standpoint) is that there are too many variables in the android world to code an app once to run successfully across the ecosystem.
Say for example you've got an app that requires typing (an e-mail app).
You have to design a version for on-screen keyboards (because it'll use part of the screen real estate) separately from a version that uses a hardware keyboard. They don't need to be separate apps, but you need to design (visually at least) for both scenarios, or you end up locking out a good portion of the people who use android devices.
This design (and resultant porting) is exactly what killed the feature phone app market. Developers spent too long making ports of an app for the Sony w810, w900 LG VX9600, Motorola RAZR because each one implemented things JUST different enough, regardless of the JSR being implemented. Then you had to test each one fully.
Sure, there are 100,000+ android devices out there, but they're across a wide set of carriers and hardware, so in order to sell your app on all 100,000 of those phones you've got to tweak your app for each device.
Conversely, with the iPhone there's one hardware platform. One way to implement a keyboard. One way to call the Camera API (and if there's no camera, the app doesn't need to do anything different). This makes an app developers life MUCH easier since they only need to design and write ONE app to reach all 2+ million handsets out there, Apple's draconian and confusing app store submission policies not withstanding.
So fragmentation will ALWAYS be an android issue until they say "here is our reference hardware platform(s) -- you must use of these three sets of features when building hardware." Coincidentally this is exactly what MS is doing with Windows Phone 7 -- three hardware platforms, that's it. You still have to design your app three times, but at least you know that if you design for one hardware platform, ANY device within that platform by ANY manufacturer on ANY carrier will have the same exact limitations and abilities.