MIT's Cheetah robot has finally been let off the leash -- and boy can it run. Watch as it bounds across a grass field, and even jumps over a hurdle. It isn't quite up to the evolutionary magnificence of its biological counterpart, which can hit 60 mph in a couple of seconds, but it's still pretty impressive. 'Our robot can be silent and as efficient as animals. The only things you hear are the feet hitting the ground,' says MIT's Sangbae Kim.