Eric Goldman of the Technology Law Blog seems to think so and I agree. The Communications Decency Act was passed in 1996 and later was interpreted by courts to immunize internet service providers form torts committed by users of their systems. In specific, it says:
"No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider."
This means generally that a plaintiff cannot sue the operator of a site for defamation for comments made by a third party. While no case has squarely addressed the issue at hand, it would seem that Section 230 of the CDA would prevent a plaintiff from suing the operator of a site for hyperlinks to alleged defamatory content. The opposite conclusion would lead to absurd results. Any reference to alleged defamatory material could be the subject of a lawsuit. This would cage speech on the Internet.