The work can vary widely, which I find interesting and encouraging -- VR is becoming a very general-purpose tool rather than a niche for a few narrow fields. ...
Sandys VR's insight:
Very interesting approach on position tracking and wide-area walking. It even works outside in the open with GPS supporting the gyroscope/accelerometer sensors. I had the pleasure to test a protoype at IEEE VR in Orlando this year. It is a little jumpy and not 100% precise but it works. You get a backpack with a laptop, an HMD and two sensor taped to your shoes, or better clipped to your shoelaces. I actually ran into a closed door because they weren't watching out for me and I was just immersed in the virtual environment ;)
Eric Hodgson also showed us some charts with tests he ran. Actually the graphs look pretty convincing. He compared the precision of his system with a WorldViz PPT system (accuracy <0.25mm over 3x3x3m volume) and it wasn't that bad. I don't remember the exact numbers though.
To put it in a nutshell: I am really looking forward to his final results. This would give us new opportunities in position tracking and will open entire new possibilities in terms of utilizability of VR.