I've been actually looking forward to this for a long time, and this is the first hmd that is design towards gaming and not as a futuristic asset.
First word i heard about this was on an interview with carmack. He actually got his hands on this prototype for some time and is developing support for the upcoming doom3 bfg edition for it, which he showed off to the press there.
In his keynote on the quakecon he got quite indepth about the whole issue, what the problems still are, where it can be improved and issues that are not quite solved yet.http://www.youtube.com/watch?v=wt-iVFxgFWk
(3:30h, talk about the hmd starts around 50minutes or so)
All in all this appears like a very promising project and i wish i had 300bucks on my hands to actually get one of those to tinker with, and unfortunately my birthday is a bit farther off