GreenWheel - easy electric kit for cycling

From Discovery News

Discovery News has this story about GreenWheel a system being developed at MIT. The cool thing about this system is that everything is contained in the wheel. Power generation, energy storage and propulsion are all in the dinner plate sized hub pictured above. The throttle is connected wirelessly via bluetooth. That means you can just swap the wheel on to a bike, trike or HPV, attach the throttle and ride away. You can still pedal the bike, which doubles the range while under power. From the article in Discovery:

Under its current configuration, a bike powered solely by a single GreenWheel (front, rear or both wheel can be equipped with a GreenWheel) has an estimated range of 25 miles. Pedaling the bike doubles the range under electric power, provided the rider isn't traveling at the nearly top speed of 30 miles an hour. The bike can be charged by pedaling or by plugging it into the electric grid.

I could see investigating this, it makes going car-light or car-free much easier, the target cost is a few hundred dollars. For that price I would happily add such a wheel to a cargo bike or utility bike such as the Rans Hammertruck . I would love to get one of these wheels for a trike to give my dad more mobility as well.
(h/t Treehugger)