Here are the 5 entities supporting the BeaglePilot project (a.k.a. push the AP_HAL_Linux of ardupilot):
To this we should add many developers doing a great work. All of it on the behalf of the Open Source Drone community (btw, anyone heard something else about the DroneCode Foundation?).
So how far are we on the road? Well, in the last weeks we've had good progress. We fixed several issues with the SPI bus managing to get better data form the sensors. We even compared it with the APM2.
It seems we have good enough data to run it on a Rover (and maybe on a plane) but it seems like it's still no good for a copter.
We will keep pushing it forward. Thanks to everyone for the support and interest.
Edit: Thankfully, i was pointed out of my mistake speaking solely of the initial 4 entities. Obviously the ardupilot team is one of the most important component. I sincerely hope that no one got offended and if so, my apologies.