It's a little reminiscent of a Wankel rotary engine, but produces power through a different cycle. Two things I thought that were really cool: it can use any kind of fuel and it can be supercharged by using a larger version of the engine (sans combustion and fuel injectors) to compress the air going into the engine.
The engine was developed to use with UAVs (Unmanned Aerial Vehicles) like the Predator. It generates more power in a smaller package than the engines used in drones while also using less fuel to do so.