Is Alterman serious about suing O'Reilly for defamation? I'd love to see it, but I'd be worried for Alterman. As Sidney Blumenthal knows, if you're a public figure, suing someone for defamation usually brings nothing grief and huge lawyer bills:
On June 15, Washington Post "Reliable Source" columnist Richard Leiby reported that Eric Alterman -- The Nation's media columnist and author of the 2003 book What Liberal Media: The Truth About Bias and the News -- has threatened to sue FOX News Channel host Bill O'Reilly for defamation unless O'Reilly retracts his statement labeling Alterman "another Fidel Castro confidant," which Media Matters for America reported on May 4.
http://mediamatters.org/items/200406150005
If Alterman goes through with it, I hope he has a killer lawyer who takes the case on contigency