Photo-John recently posted his list of the top five cameras for mountain biking on MTBR, and given how well that hits two of my favorite hobbies, I couldn't help but re-post it here.
I haven't used any of these cameras, but the choices and reasons for making them seem sound. In my case, I've opted for the GF1 in place of Photo John's #2, the GH1. The GF1 gives ground to the GH1 in EVF quality and it shoots video at 720p instead of the GH1's 1080p, but is smaller in size and comes in a kit with the lovely 20mm f/1.7. I can see someone going either way.
His #1, the Canon 7D is also a good choice of DSLR based on reviews I've read (and being a former Canon 30D user). I use the Nikon D700 as my DSLR, which has the advantages of being full-frame, better in low light and better sealing (and, IMO, handling). It gives up ground on being much more expensive and doesn't do video at all.
In any case, it's a good list and worth checking out if you're in the market.