For a little while, I've been casually watching the development of quadrocopters like the Parrot AR.Drone. The camera-equipped, iPhone-controlled Parrot is a pretty neat toy, but it's got nothing on these drones. A student at the Swiss Federal Institute of Technology Zurich has taught a pair of quadrocopter drones how to play catch—autonomously. Check it out:
As Robobub points out, getting quadrocopters to juggle an inverted pendulum is really difficult, requiring lots of math and even a learning algorithm "to correct for deviations from the theoretical model." Masters student Dario Brescianini seems to have nailed it, though.
I, for one, welcome our new quadrocopter overlords. It's probably a good thing they're Swiss.