Check this out -- Kiva Systems' robots in action in a Staples warehouse. I've seen one of these up close before (carrying a person, actually)... it's pretty neat. The bearings used to keep the payload in the same orientation must be pretty crazy. When I saw one in action, it used little bar-code type labels to follow on the floor, but there's some net intelligence directing them because these guys are all moving in an overall organized fashion -- this article from the video producer, Fast Company, suggests that "blinking blue lights" help coordinate them somehow. At some point in the future we'll talk with the creators and see what we can find out!
Video by Fast Company