An interesting development from the UK:

In the first case dealing with the privacy of internet bloggers, the judge
ruled that Mr Horton had no “reasonable expectation” to anonymity because
“blogging is essentially a public rather than a private activity”.

The judge also said that even if the blogger could have claimed he had a right
to anonymity, the judge would have ruled against him on public interest
grounds. — Times Online

Back in 2003, my division chair said he would support a university blogging portal only if members blogged under their own name. That turns out to have worked out well for us.  I don’t, however, require commenters to prove who they say they are. 

The Las Vegas Review-Journal says it has been served with
a federal grand jury subpoena seeking information on people who posted
supposedly threatening anonymous comments on a story about a tax fraud
trial. — The Register