We are getting very close to being able to use open sourced 3D environments on a grand scale. Take a look at OSGrid and realXtend and consider the information that Google has servers that can be used by the tech savvy. Forward thinking minds are hard at work generating the code for virtual environments, and the open source software movement is intriguing, take the time to look at: Two Bits: The Cultural Significance of Free Software .
I looked at the OSGrid photo gallery and I was so impressed I decided to try out OSGrid myself last night. I ended up under the sea (a very nice sea I might add) and I could not move at all. Tried walking, flying, teleporting and prayer but I stayed there beneath the sea. I had no avatar either, no body, no movement, very peaceful really!