Basically, these goggles fit on your head and give you an immersive 3D view of a game with a screen that covers your entire field of vision. The view changes as you move your head up and down and side to side, simulating what it would look like to turn around in that world.
It's not an accessory for existing games the way the games are currently written. Instead, the games have to be adapted, via a developer's kit, to take advantage of the glasses. The developer's kit has been selling for a while, and the consumer's version is expected to hit the market in 2014. And I hope it's lighter and less bulky, too. I think developer kit goggles are selling for about $300 right now.
Regardless, the device (because the screen is built in) will fundamentally change the way people play and think about and play video games. A lot less fighting over the TV set. Also, I have kind of a concern that some people will step even farther out of the real world with something like this. However, imagine what it could do for someone who is a paraplegic or a near quadriplegic, or house bound due to some kind of disease or impairment?
This is a cute video of a 90-year-old grandma trying on the glasses: