Micro air vehicles that cooperate

MIT researchers are using tricked-out model helicopters, each about the size of a seagull, to demonstrate swarming behavior in unmanned micro-air vehicles (drones). According to Aeronautics and Astronautics professor Jonathan How, they're focusing on techniques for "persistent surveillance." A group of drones could act as a distributed eye-in-the-sky for a military convoy with the vehicles taking turns landing on a truck for recharging in a docking station.
From New Scientist:

In the indoor tests, up to five radio-controlled helicopters are being used to collaboratively track small ground vehicles and land on the back of small moving platforms.

A video shows one of the vehicles landing on a moving truck, while using a camera to lock onto the target and landing pad.

In another experiment, each UAV was programmed to automatically land on a stationary recharging station when running low on battery power. Another video shows two aircraft working together to track a moving ground vehicle. The UAVs automatically take turns tracking the target at low altitude.

Link to New Scientist article, Link to MIT press release