According to a DefenseReview article, an off-the-shelf UAV has been "weaponized" by Neural Robotics Incorporated through the addition of an AA12 full-auto assault shotgun. The gun can fire up to 6 rounds per second from a 20 round clip. The NRI website offers video of the robot gunship in action (MPEG format). The UAV, called AutoCopter, uses a neural network flight control system that operates in either a fully autonomous mode or an automated remote control mode that allows a human to direct the robot but prevents the human from doing anything stupid (provided you don't define flying radio control helicopters with shotguns on them as stupid). For more information, see the NRI press release. Definitely a project that fits in the "don't try this at home" category.