Ah, that makes much more sense. Having said that, where do you see fragmentation in the Java ecosystem? I don't use Java to write anything but Android apps, but I've used a few pure Java libs with Android and they all seem to work great.
That isn't to say it isn't happening, I just don't experience and would be interested in knowing where it does occur.
Blackberry is more J2ME-ish and Android is more J2SE-ish. It's possible to share engine code (I've done it) -- you'd still have to do custom UI code for each.
That isn't to say it isn't happening, I just don't experience and would be interested in knowing where it does occur.