Not very:

Anonymous bloggers beware. You may not be as anonymous as you think.

Forward Township Supervisor Thomas DeRosa has won a court victory in the action that he filed in November to uncover the identities of people who posted comments on an online bulletin board that he said defamed him.

On Wednesday, the ACLU, which had intervened in the case, turned over the Internet Protocol addresses of six individuals who made specific posts that Mr. DeRosa mentioned in his court filings.

Always remember to think twice before clicking that post button. Your computer has that IP address and your internet provider keeps track of who had what IP when. All it takes is a decision by a judge and you are no longer anonymous.