Great project! I'm actually in the midst of my own robot build using the RoboClaws and Arduino boards. I haven't explored RPi yet, but I probably will down the road. For now I'm focusing my attention on integrating an Android tablet as the "brain" of the robot that connects to the MEGA ADK board.
What motivated you to go with RPi for your robot? Any updates on yours since your post here?
I'll be posting my own project here soon, but you can check out the progress on YouTube or on ROVer's site... links in my signature.