Michael Kanellos, Staff Writer at CNET News.com has an excellent article on a company called GyroBike
"The company, a spin-off out of Dartmouth College, is coming out later this year or early next year with a gyroscope/flywheel that fits into the front wheel of a kid's bike. When a child begins to go off-balance and fall over, the gyroscope corrects the path of the bike and props it back up. As a result, kids don't need training wheels to learn how to ride".
The article is titled: Start-up aims to ditch kids' training wheels