Here's a couple of recent posts about bears I found by using the search tool:

ETS Bear Post 1
ETS Bear Post 2
ETS Bear Post 3

I think the consensus is that bears have their own personalities and some respond differently than others. Supposedly black bears are more predatory and grizzlies are more defensive in nature. Either type might bluff charge if you startle them, attack if they perceive you as a threat to cubs, or decide you'll make a tasty snack if they're really hungry.

UDAP makes the "Pepper Power" bear spray and has some tips on their web site: www.udap.com/safety.htm