Via DIY Drones comes this video of the Stanford STARMAC (Stanford Testbed of Autonomous Rotorcraft for Multi-Agent) quadcopters:

STARMAC, the Stanford Testbed of Autonomous Rotorcraft for Multi-Agent is a testbed of 6 quadrotor helicopter unmanned aerial vehicles that fly indoors and outdoors to experiment with autonomous agent algorithms. This video presents an overview of the control system, the vehicle capabilities, and the experimental applications for the testbed. Results of many experimental flights are shown, along with some fun flight results that push the limits of what the vehicles should be able to handle.

Stanford quadcopters rock!