Have you seen this little guy? His name is Romo.
Image all the fun we can have. http://romotive.com/meetromo
+1 to this!
This is the first I've heard of it, but it looks interesting.
It reminds me (naturally) of the '80s Logo turtle. And therefore has obvious kidergarten education application possibilities.
Maybe a bit expensive? $99, and shipping to UK adds $40!
But interfacing to R-Pi would (I hope) be easy.
It uses the same power connector as our Pi, so may be using a battery of a compatible spec - a small mod would allow the Pi to get its power from Romo! - if the Pi doesn't need the full 5V for its audio out, then as long as Romo's battery has enough oomph to drive the SoC (and the GPU should be virtually shut down since there would be no video output) it should be good to go with a model A Pi.
The more I think about this the more excited I get! Just going out to join the Romo fraternity!