We ban griefers. We can even IP ban someone. But if someone really wants to get at a given blogger, they can via anonymous accounts.
For those of you who have blogs who feel like they're getting stalked by trolls and other jerks, you can stop them.
When you create an article, only allow registerd users to respond to your article. That way, you have some say over who can interact on your site.
It's important to keep perspective on your blog site - IT'S YOUR OWN BLOG. You don't have to put up with jerks coming on and trolling you. If you find yourself getting angry or upset about people's responses, don't despair. Just don't let anonymous users respond and if registered users are upsetting you, just add them to your black list archive. Your blog is like having a room in a huge house. You have the right to decide who can come into your room.
It's all about having fun. If you're a liberal and you feel like a bunch of "right wing kooks" are spoiling your writing with their responses, you can stop them. Same if you're a conservative and those "liberal nut cases" are bothering you. It's not about freedom of speech. THEY still have freedom of speech - on their own free blog where they can write. On your blog, YOUR rights take precedence over the "rights" of people who would respond.
I black list people all the time from my blogs. Not because they disagree with me but usually because they just add angst and nastiness to the responses (or they spam for things). If you want your articles to be a debate about politics or computer hardware or whatever that's fine. But on the other hand, if you're writing about your job or your kids or a movie you saw, there's absolutely no reason you should feel like you have to allow some sad griefer to spoil your enjoyment.