I was just reading This Article from the BBC.
I wouldn't like anyone to post anything mean on my site(s) which is why I don't allow annonymous comments. I wouldn't put anything mean either. I am careful not to write anything which might be offensive (unless you find knitting or jogging offensive!) and the nearest I come to controversial is politics.
When I read Boris Johnson's blog I sometimes find his writing controversial. He is a politicain though!
I guess the problem is if you're a regular person who gives out more information than they perhaps should, then you might be at risk. If someone were to put a post on my blog threatoning me, I'd be able to track them down, and I'd also know that although they know which city I live in, I bet they couldn't easily find me. That said, I'm probably in the phone book.