It all boils down to what firearm you can shoot fast and accurate. Of course, you'd want enough gun for the task.
I know of several hunters that carry 10mm's into grizzly country. Personally, i've always packed my 45 colt or 44 mag loaded with 300+ gr hardcast at 1100 fps. I have also packed my 357 loaded with BB 180 gr loads before. I also understand that any pistol round is marginal at best against any angry bear. But.. I'd rather have one of my pistols while out picking huckleberry and packing around baskets than nothing at all. It does no good having some super magnum if you can't place a cylinder full where they need to go.
http://www.youtube.com/watch?v=CqABkG1JpHM
I wish I could draw my pistol and fire that fast
When out elk hunting my standard rifle will do the job - my .358 Win