While fuel cells are several years away from replacing the standard alkaline or rechargeable battery, Canon in Japan has showed off an EOS KISS Digital N camera (Japan's equivalent of the US Rebel XT) that runs on a hydrogen fuel cell.
The fuel cell fits in the battery extension grip of the camera and provides the same amount of power as the normal lithium-ion battery. Canon promises that the fuel cells will eventually pack three to five times the power of similar-sized lithium batteries. In addition, they could be "charged" in a few minutes, versus a few hours with current batteries.
The company did not say when the fuel cell will become commercially available.