I'll answer my own question.
It's pretty easy to set up J2ME Polish to produce blackberry apps. I'm producing .cod files right from netbeans, and as far as I can tell, the applications are pretty nice looking.
I was able to port my old AIM chat application over and get it running with minimal fuss. If I spent more than 3 hours on the effort, I'd be amazed. And if anyone wants to play with an old, antiquated AIM app, let me know.
Now, I'm off to do something useful with the platform.