Q Robotics (early stars from iRobot that liked startups so much, they needed to leave and start another once iRobot went public)
http://qrobotics.com/
You don't really need to know anything about robots to work on them. The best groups are made up of specialists that understand a bit of everything, but are essentially software|hardware|electrical|systems engineers at their core.
MekaRobotics (by Aaron Edsinger, MIT star behind Domo) http://mekabot.com/ http://people.csail.mit.edu/edsinger/domo.htm
Willow Garage (former early Google employee founder) http://www.willowgarage.com/
AnyBots (Trevor of YC's company) http://anybots.com/
Q Robotics (early stars from iRobot that liked startups so much, they needed to leave and start another once iRobot went public) http://qrobotics.com/
You don't really need to know anything about robots to work on them. The best groups are made up of specialists that understand a bit of everything, but are essentially software|hardware|electrical|systems engineers at their core.