Purely an academic question from my point of view, but thousands of anonymous bloggers must be concerned about being "outed" after this ruling from the British High Court.
I believe bloggers generally should have the courage of their opinions and should be up front about who they are. Anonymity places the burden of proof on the reader. That's problematic. To me a hidden blogger may be hiding something else. But at the same time, anonymity may be the only way to safely get a story out.
Having said that, the blogging cop in the story broke his professional oath of service. The court ruled "it is not part of the court’s function to protect police officers who are, or think they may be, acting in breach of police discipline regulations from coming to the attention of their superiors.”
So the right to anonymity is not challenged, except in the case where an oath already exists.