This article at TechEBlog talks about MetaMersion, a company that wants to bring games into VR. The video is really cool. Also check out the photos

From the website :

“The backpack (..) contains software that is read by a 6-by-6-foot grid of motion sensors attached to the ceiling over-head and telles the computer where and how the player is moving”
“Because the most popular games are “first person shooter games”, according to Ebersole, the system includes a realistic replica AR-15 machine gun”.

Damn they stole my idea =)