CatEye of Japan has had a similar product - the GameBike - for 2+ years.
Unlike CatEye's GameBike, the GamerCycle isn't interactive, it can't be used as a 'rally car' or other on-screen vehicle, it supplies the power source.
CatEye's product is a box only, you have to supply your own bike and GameBike works only on PlayStation2.
GamerCycle works with XBOX, PlayStation, Game Cube and other video game units.
XMAT says on its website: "Children need healthier lifestyles now. There are hundreds of physical fitness products for adults, but nothing specifically designed to help get kids started on the right path. And since kids on average play video games more than an hour a day, converting this time into a healthy activity is a great way to start getting healthy. Exercise is best when it's fun, rather than something to be dreaded or rebelled against."
XMAT's GamerCycle costs $349 direct from the company.