Section 230 of the Communications Decency Act.
Section 230
Children of America, Inc. v. Magedson
Galveston Independent School District v. Tetley
Lackner v. Sanchez
Citizen Media Law Podcast #3: News Media Clampdown in Pakistan; Sam Bayard Interview on Internet Solutions v. Marshall
Anthony Ciolli, Former Director of AutoAdmit, Dropped From Lawsuit
Legal Threats Database Preview: Internet Solutions v. Marshall
VeriResume v. Marshall (Email)
Citizen Media Law Podcast #2: Legal Threats Database; Orthomom Defamation Action; Iranian Blogger Sued in Canada
Iranian Blogger Hossein Derakhshan Sued for Defamation in Canada
Video Professor v. Justin Leonard
Warman v. Fournier
Video Professor v. Does
Citizen Media Law Podcast #1: Federal Shield Bill; Co-Blogging and Legal Threats; Phoenix New Times Arrests
Loan Center of California v. Krowne (Email)
DirectBuy v. Leonard
Unknown Homeowner v. Madison
Co-Blogging and Cease-and-Desist Letters
Stratton Oakmont v. Prodigy
Cubby v. Compuserve
Pages

Description:
In March 2007, Children of America, Inc., a childcare provider, sued Ed Magedson and Xcentric Ventures, LLC, the owners and operators of the Ripoff Report website, for defamation in Arizona state court.
Ripoff Report is a consumer reporting website that invites consumers to file and document complaints about companies or individuals with whom they've had negative business experiences. Users of Ripoff Report posted a number of critical comments about Children of America.
Children of America sued, arguing that, in addition to publishing user comments, Ripoff Report itself augmented and/or added headlines for the allegedly defamatory postings.
The defendants moved to dismiss the claim based on CDA 230, which protects information service providers from liability for the defamatory comments of third parties. On October 24, 2007, the Arizona Supreme Court granted the motion with respect to those statements allegedly created by Ripoff Report users, but allowed the action to continue with respect to those statements allegedly authored by the defendants.
Update:
12/1/08 - According to the Case Docket, the parties have settled the case.