Internet Trolls: The Law is Changing.

The government are to take steps which will make a "troll" liable to prosecution for defamation of character against someone, rather than the website master...
BBC News.

So take care that what you say about someone is true, as the website owner can be forced to give the details (name, address etc) of someone, who a claimant thinks may be defamatory.

Here's the Guardian's take on it...Guardian
and here