As you may recall, Photography Bay previously reported on Canon’s efforts to patent a method for using fuel cells to power your DSLR. A newly published patent application (US 2008/0180565) sheds a little more light on things to come with fuel cell powered DSLRs.
Canon continues to push its fuel cell development by devising a method for powering not only the internal DSLR body electronics, but also external components such as lenses and hotshoe flashes.
The present invention relates to an electronic equipment system having fuel cells, and more particularly, to a camera system in which fuel cells are provided to a camera body and a connection device connected to the camera body. 
Say Goodbye to AA Batteries
Essentially, Canon wants its fuel cell to power everything you attach to your camera. That’s right. No more AA batteries to stuff into your camera bag.
. . . dual battery control of detecting a remaining amount of the battery in each of the devices and determining the state of each of the batteries to control electric power supply, which makes the battery control complicated. 
The patent is a little long winded (as patents can be); however, the gist of it is to have a single power source (i.e., the fuel cell) and that source powers everything (e.g., hotshoe flash).
. . . an electronic equipment system in which fuel cells are provided to an electronic equipment body [ed., a DLSR body] and a connection device [ed., a hotshoe flash] connected to the electronic equipment body, and in which detection of a battery remaining amount and control of electric power supply can be performed under unified management [ed., one fuel cell], thereby enabling simplification of the electronic equipment system and improvement of power generation efficiency thereof. 
The blissful absence of partially charged batteries and wonder whether the four batteries you stuffed in the side pocket last week were good or bad. No more battery chargers plugged into your kitchen outlets. Basically, the best invention since sliced bread . . . ok, maybe not, but it is interesting nonetheless.
What’s It All Mean?
First of all, Canon’s always going to push digital imaging innovation to the next level. Clearly, the competition is too stiff to try to lay low now. Canon stays at the top of the patent filings charts due to this drive.
With this changing tech comes the new gear. In this case, fuel-cell DSLRs means a lot of new gear – maybe even a new system. At the very least, it calls for the purchase of new speedlights with your camera body. I suppose, however, that Canon could allow backwards compatibility of battery-powered electronic flashes with this fuel cell power source.
Finally, it should lessen our carbon footprint as photographers in the digital age. Many of us are starting to think real hard about environmental issues in this changing world climate and economy. How many fewer AA batteries would our landfills see if the every digital camera user suddenly switched to fuel cells? It’s a start.
If you want to read the whole patent, feel free to look it up on the USPTO website (patent application # US 2008/0180565) or follow this direct link.