My nano-sumo bot project is still going. I've had a number of attempts at getting under the 1 cubic inch size barrier. And it looks a lot closer now. I just discovered some 402 sized SMD LED's from LUMEX. So I did a Atmega8 (MLF formfactor) PCB using 402 sized parts on it as well. It eeks out a little bit more space on the PCB. I still have a 603 sized component PCB just in case.
Now if I can only find some small rechargable Lithium-ion battery cells small enough to work. using non-rechargable cells sort of sucks as they are very expensive. I see tantalizing pictures, but no one selling them yet. Or at least selling in small quantities.