Courtesy of Harry Lewis, author of the very insightful book Blown to Bits:
Ethical or not, it looks like using [fake names to protect your privacy online] could set you up for doing some hard time in a federal penitentiary. Lori Drew was convicted of violating the Computer Fraud and Abuse Act because the jury deemed that by creating a fake identity as a boy, she had gained “unauthorized access” to the servers of MySpace, whose Terms of Service state that registration information must be truthful. By that logic, anyone using Bug Me Not is setting themselves up for indictment on the same charge.
The rest of the post, including some context if you’ve never heard of the wonderful web service Bug Me Not, is available at Mr. Lewis’s website here. And if you’re a little shaky on the technological side of some of these issues, I recommend Blown to Bits to help you understand the issues of the day.