Practical Motion Capture in Everyday Surroundings
THIS IS NOT A COMMERCIALLY AVAILABLE PRODUCT
This self-contained motion capture suit uses ultrasound to allow the recording of motions in any setting, as opposed to traditional motion capture systems that are confined to a studio. Published in SIGGRAPH 2007.
More info (PDF):
http://people.csail.mit.edu/jovan/assets/papers/vlasic-2007-pmc.pdf