Just started looking into a bit of programming for the android and was playing with this simple example. It runs just fine when compiled in Standard mode, but when compiled in Android mode and run on a nexus one the rectangle just sits there, not moving at all. I'm using boxwrap2d from this link:
http://jbox2d.nfshost.com/processing/boxwrap2d.zip and processing 0194.
The other thing is that I have to call physics.defaultDraw() otherwise nothing gets drawn at all.