Indeed, there was a great example of collaborative VRML on-line in the late nineties, by exploring a 3D 'house' together you could unlock certain features, everyone ended up in the bouncy fireplace! We were very excited about the potential, it's only been 20 years to wait for the hardware to catch up :)
The hardware has been ready for 15 years already (just think of all the 3D multi-player games and Second Life clones out there).
What we had to wait for was the technology to be reinvented a dozen times before client side web languages finally reached the same point that desktop software development was 20 years previously (and let's not forget the prolonged stagnation in web technologies as pioneered by the dominance of IE6).
