3D Vision allows you to play games in stereoscopic 3D if you have the 3d Vision kit, a display that supports 3D vision (120Hz monitor,CRT, or other support display like DLP), and the 3D Vision driver installed.
Making a game 3D Vision ready means, as stated above, makes sure things like shadows, sky, crosshair, etc render correctly when 3D is enabled. The technology is NOT like the 3D in the theaters. Games are not automatically forced into 3D if you do not have the required hardware and software and enable it. You will not see any difference or performance decrease if you are playing a 3D Vision ready title without the 3D. Some popular games that are already out that are 3D Vision ready are:
Battlefield: Bad Company 2
Batman: Arkham Asylum
Dead Rising 2
Just Cause 2
Metro 2033: The Last Refuge
Resident Evil 5
Trine
Civilization V
Lost Planet 2
Mafia II
Chances are many of you have played some of the games I just listed and maybe didn't even realize it was a 3D Vision title without any detriment to your gaming experience. I am just asking Bethesda to add another feature to the game to enhance the gaming experience for those that are able to use it.