"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/
Full decision: http://www.courtinfo.ca.