The rules for Robosumo contest can be found here.

This contest was a modified sumo competition, allowing for slightly larger robots to accommodate more peoples designs. There were 10 entries (10 robots, 8 humans) that were divided up into pairs for competition.  Each pair competed for best of three matches.  The primary matchups determined the winner.  All the losing robots had a second chance to compete against each other which determined 2nd  place.  Pictures of all the competitors follow along with the results.