Quadrotor Update
I've received couple of emails asking whether or not the project is still going on, short answer is yes we are still working on it, long answer is that, things are progressing very slowly due to logistical problems, every shop in Turkey or Europe seems to be out of Beagleboards looks like I won't be able to get one until the end of november, this did gave us a lot of time to read though.
One of the first things that I figured out is, Beagleboard is not a faster Arduino that is running Linux even though it has I/O pins, it requires a lot of custom electronics in order to interface with various sensors on top of that very few people actually uses them so I decided to add an Arduino to the mix and use that to interface with sensors/motors.
I initially thought an IMU for stabilization combined with a GPS for navigation would suffice, turns out I under estimated GPS errors, people report altitude errors up to 10 meters which makes GPS useless for altitude hold.
So right now our theoretical setup includes a 9 [DOF](http://en.wikipedia.org/wiki/Degrees_of_freedom_(mechanics)) IMU for stabilization, GPS for navigation, a pressure sensor for altitude hold, all connected to the Arduino sending readings to the Beagleboard at 50 hz, all calculations done on the Beagleboard and new motor speeds send back at the same rate which should be enough to keep it stable. Of course theory never works in real life so we'll see how things pan out.