I just saw this on another website today. I thought I would pass it on.
"The California Supreme Court ruled Monday that bloggers and participants in Internet bulletin board groups cannot be sued for posting defamatory statements made by others.
In deciding a case closely watched by free speech groups, the court said a federal law gives immunity from libel suits not only to Internet service providers, like AOL, but also to bloggers and other users of their services."
http://www.msnbc.msn.com/id/15817955/
It seems like the key word is "by others" - the ruling doesn't give an individual the right to defame someone, but it appears to extend ISP protection to bloggers, forum operators, etc. It will be interesting to see what in-depth analysis of the decision reveals.
Full decision:
http://www.courtinfo.ca.gov/opinions/documents/S122953.PDF