Made with Processing. Uses SMS library by Shiffman. shiffman.net/p5/sms/
The newer Mac laptops come with a built in sudden motion sensor that is meant to help protect the harddrive if it detects, for example, the computer is bouncing down a set of stairs.
Compadre Shiffman wrote a nice clean library which allows Processing to utilize that data. I just assumed it would pay attention to tilt and little else, but imagine my surprise when I found it paid attention to inertia as well.
V3ga has a nice clip showing the rotation aspect of the sms.