You should read (and subscribe to) Damian's troll-killer post and the comments though, just in case Google changes the layout again or there's a bugfix. For example when I've the troll filter activated, I don't see threads when a troll posted the last reply.
Remember: The canonical treatment of trolls is ignoring their posts, regardless a particular posts's insanity or the lack of it. Not even insults, slander or name calling justifies a reply to the troll. If necessary, forward the post to your lawyers, but don't enter a discussion with a troll because that feeds their ego and encourages them to produce even more crap.
Hat tip to ThoughtOn
Related post: What to do with [troll's handle]? by JLH
Post it to