There has been some attempt to use the G1 as a remote control for a robot. See here http://code.google.com/p/srv1console/
While this is a nice start, it occurs to me that the idea could be taken much farther as the G1 (and other soon to follow android based cells) sports an application processor, storage, camera, etc. It seems to me that one could use a cheap microcontroller for PWM motor control and things like that, but use the phone's appication processor for more of the heavy lifting artificial intelligence kinds of things. I would think that the easiest way to connect the microcontroller with the cell would be blue tooth, as the miniUSB would require tinkering with the kernel and that's probably not an option for most people.
Anyway, I've done a little digging and I found this library for video processing http://code.google.com/p/jjil/ and a website by Oleg in Russia who has gone pretty far with J2ME http://www.robohobby.com/. I realize that java is too slow for anything really processor intensive (the jjil library might speeds things up a bit) but the application processor on the phone has to be way better than most of the micro controllers out there.
What do you guys think? Would it be possible to build anything like serious robot functionality (stereo vision, spacial mapping) this way, or am I wasting my time?