The MTi-G is an attitude-heading reference system (AHRS) which fuses information from accelerometers, gyros, magnetometers, barometer and GPS. It's a pretty tiny unit and although space isn't an issue for us in the GCDC this is an important factor for future robotics projects here at Halmstad. Since we want to send as high quality information as possible about our own car to our "opponents" (our fellow platoon members) we'll be using the MTi-G for situations which are tricky to handle only with our Trimble RTK GPS (which has good absolute location precision but is pretty vulnerable to signal dropouts and doesn't provide very useful attitude data).
The documentation that came with the MTi-G was really nice and it was a pretty quick job to integrate it into our LCM-based system using its open serial communication specification.
The following video shows another XSens sensor (sans GPS) in action:
