We don't know whether we should be terrified or overjoyed. We've just come across a video demo from the University of Pennsylvania's GRASP Lab that shows an autonomous quadrotor helicopter performing "precise aggressive maneuvers." And trust us when we say, nothing in the foregoing sentence is an overstatement -- the thing moves with the speed and grace of an angry bee, while accompanied by the perfectly menacing whine of its little engine. See this work of scientific art in motion after the break.[Thanks, William