Here's a video to show some of the work going on at the GRASP research labs at the University of Pennsylvania. Work has been done on trying to generate dynamically feasible trajectories and controllers to guide the quadrotor through space. It is shown making aggressive manouveurs through small gaps and slipping between other quadrotors. The work looks at developing families of trajectories each built up as sequences of smaller trajectories each with their own individual controller. It's interesting work and it is hoped to be of use in surveillance and search and rescue operations. It's more likely (definite) however that it will be used for "defense" purposes.
Anyway enjoy the video.
