ghing: I'd assume it's a bad thing because more than 1/2 the people who visit your site can't be bothered to dig deeper. I had 67% bounce for a long time, recently saw it in the 40% sometime as well.
I should add that if you have lot's of social bookmarking traffic.... Chances are you will always have a high bounce rate as they stereotypically don't stay long regardless of how interesting it may be
