Apparently FIA boss Max Mosley came to an agreement with the car makers to go green by 2010.
It would be a great idea. I already hate that they can refuel during the race. A simple rule change to have them make race cars that go the full distance on one tank would also bring lots of innovation for fuel efficient engines. By 2010 the Formula One cars will have engines with 675hp and an additional 80hp from an electric engine that is charged when the drivers brake during the race.
Via FT Deutschland (German).