I'll have to look into that. I've played a bit with an accelerometer connected to a Raspberry Pi and that's some truly amazing tech.

What I used is small pc board that's about a 1" square and has a magnetometer and an accelerometer on it. I hooked it up to a Raspberry Pi computer and made an animated compass. I made a video of it and blabber on a bit about how I hacked it together and posted it on YouTube.

I didn't try to measure distance with it though. I didn't even know that was possible but those Apple engineers are a lot smarter than me .