In traditional print publishing, the editor is legally responsible for what he puts in the paper, regardless of whether they wrote it. That is why they do careful fact-checking before printing letters to the editor. . . .

It will be interesting to see if the courts apply the same standards of journalism to web publishing, like forums and blogs.

It looks like the liability for defamation can depend on the country where the parties live:

http://dba-oracle.com/oracle_news/2005_9_1_liable_blog_comments.htm

For example, this Australian libel web site notes that linking-to or otherwise republishing a libel, is itself a libel:

In principle republication of a defamatory statement is itself a libel.

It is no defence to say that what is published is merely a repetition of a statement that was previously published and that did not incur prosecution. In principle every person who repeats or republishes a defamatory statement faces the same liability. . .

Australian law is an adversarial system, in which a defamatory statement is assumed to be false and must therefore be defended. Truth was allowed as a defence in defamation for first time in the UK under the 1835 Libel Act but – in practice – using that defence can be difficult.

Also if someone says – hey don’t use my name – it could mean a few things none of which are good and none of which you want to put yourself in the middle of.