I thought this was interesting. Defamation laws in Australia have been used to sue a newspaper for saying some fairly unpleasant things about people who provided character references to a man accused of the possession of child pornography. The bit I found interesting was that the newspaper allowed a comments section; it was accepted that this entailed the comments being published under that masthead.
That means that a) anybody who has commented under an internet news story has now officially been published by that paper, b) judges are going to have to get to grips with the concept of people who write "firsties!!!1!!! LOLZ" and nothing else and c) we can potentially get the hell sued out of our least favourite newspaper. Or us, depending on how far they plan to take this.

If anyone comments on this, please keep it non-defamatory.