2600fromatari; that sounds like the story about John Muir, who was said to have charged a bear like that, and frightened it away. Pretty risky.
When I was a kid I remember that the advice was to lay down and play possum, and now it's to make a lot of noise, and throw rocks and make yourself appear as large as possible (holding your jacket open, over your head, etc.) - but I don't think that's something I'd try with a grizzly. With a grizzly, I think I'd just cr&p my pants.
