I would like to add a link to our new project called Next Generation UAVP.
It's an ARM7 based Quadcopter.
Our website can be found at http://ng.uavp.ch
The current state permits very stable hoovering in place and normal dynamic flight. We are using Kalman filters for sensor data fusion and succeeded in keeping the closed-loop control frequency at 1kHz. The software is very flexible and allows the implementation of different closed-loop controllers beside each other. We implemented a small home-brew operating system allowing real time controll and cooperative multitasking distributing the rest of the cpu processing power to several non-realtime tasks like consoles and communication endpoints.
I blogged a bit about the project at http://amir.ch