Found the following on digg.. It's very very very similar to a gizmo made by ZAP a few years ago, however ZAP's thing required the user to be wearing roller blades. This appears to have the rider standing on a platform. It looks easy to build using something like a bicycle hub motor kit.
http://www.5min.com/Video/Presenting-The-Easy-Glider-35791835
I would think it would lose traction when going up almost any incline with so little weight over the drive wheel, my guess is that it can't pull you from a dead stop.