Hi
As per the links provided and the fact I have just got myself a juicy 1st on this very subject...
Yes, technically a website or ISP can be sued for a comment made by them and also comments made by a third party.
However, they must satisfy the common law and statute laws governing defamation, as well as the EU directive on E - Commerce.
This is a very topical and contentious area of law and despite the straightforward nature of defamation, the reality is that taking action for Internet libel is hugely expensive and the chances of recovering any damages is negligable.
Bruce Grobelar took an action against the Sun ( or Mirror) newspaper in the 90's and despite winning his case for libel was only awarded �1.
risky business!!
J x