The GRASP Lab at the University of Pennsylvania is already famous for its quadrotor tricks, including bots that can fly through windows and hula hoops, build structures, and even land on each other. Now, those big bad quadrotors have been shrunk down into much smaller "nano quadrotors," and the GRASP Lab has been playing around with lots of them.
I would guess that one advantage of having smaller quadrotors (besides sound even more like a swarm of giant angry bees) is that you can cram more of them into a given space, allowing you to perform more complex swarm behaviors. And, as you can see from the video, they're eminently tossable, and it sort of looks like you can just chuck 'em like ninja stars and they'll self-right and stabilize themselves.
If my counting is right, up to 20 of these things can fly in formation all at once, and it's very impressive to see them make a series of different 3D shapes. This makes me think of MIT's Flyfire project from February 2010, which would have (or will?) use very large swarms of small helicopters with synchronized LEDs attached to them to form a huge dynamic 3D animated display. Since Flyfire hasn't happened yet, I'd love to see what UPenn could do by sticking LEDs on their fleet of 20 nanoquads and taking some new view with the lights off. Oh, and take some long-exposure pics while you're at it, too!
[ UPenn GRASP Lab ]