It seems Virtual Reality is gaining popularity again. I remember back in the 90' when VR was the big hype, but never took off because og the lacking hardware - both to produce the images fast enough as well as capturing user input accurately enough. There was also the problem with lag since the hardware available needed time to crunch the numbers.
Nowadays there's no question of the hardware being powerful enough and as we've seen the last couple of years the sensor technology and finding innovative ways of deploying it certainly has improved.
A while ago I came over the VR game gun which shows how "easy" it is to use off the shelf components and software and make something quite cool - as long as you have an idea.
This system, although functioning, would require a very larg venue to be practical so keeping yourselfe stationary, but still moving around in the virtual environment has been one of the other big issues needing solving. Creating a big sphere, ie a gigantic hamster ball, where you can round around inside is not a new idea, but I haven't seen anyone actually creating such a device until now.
My biggest concern about this sollution is momentum. No matter what material you decide to use to construct the sphere it will have considerable mass and coming to a complete halt after running will test your balance. I would love to try it out though :)
More information at the VirtuSphere homepage.