The California Supreme Court has ruled that web sites are not liable for libellous material on those sites if it was written by a third party. In other words, a plaintiff can go after the libelling party in court, but not the online medium that was used to publish the libel, if there is no relationship between the two.
This is good news on the free speech front. It helps relieve some of the worry I have concerning running web sites that allow commentary by unaffiliated people.
Of course, there will probably be cases where a web site owner tries to pass off inflammatory material as having come from a third party, but I think existing remedies should suffice for that sort of thing.