The video capture feature does work, you just need the latest version:
http://sumoudou.org/whats-new.html (2009-12-19-042222 Added：Record screencasts on Nokia N900)

The FM transmitter power increase seem to be working too, but of course I have no professional way of verifying it. I get no static noise in my car anymore so.. =)
Look at this thread for info: http://talk.maemo.org/showthread.php?t=38582