I've been wishing for stuff like that for years. People always bring up Minority Report, fuck, didn't anybody see Johnny Mnemonic?? Ok, so it was a crappy movie except for Dolph Lundgren, but it had the Minority Report user interface like TEN YEARS before Minority Report!!!
Also, when it comes to FPSes, we don't want just headtracking so we can look around corners n shit, we want GUN TRACKING too. I want to be able to aim myself!
Would be much more satisfying gunning people down that way, preferably if there was a hefty kickback mechanism too. Lightguns could really make a big jump by not being tied down to tracking the electron beam of a CRT, with a camera tracking the gun they'd work on flatscreen monitors too and they would be more precise.