Yes of course, afaik all decent DSLR cameras use proprietary battery packs, not AA or anything like that. They come with a charger and 1 battery pack.
The canon ones use battery packs like this:
The EOS series cameras are very power efficient so unless you use your camera alot, you won't need to charge it often. I only have a 1gb card but i can fill the thing several times before needing to charge the battery.
If you plan on taking LOADS of photos and don't want to charge or change batteries for days, you can get a battery grip that adds 2 (i think) extra batteries.
I don't know much about the Nikon cameras but it should be the same idea. They're both quality manufacturers so it's just down to personal preference for the most part which one you choose.