On the Media, a US NPR program, examines what happened when Dilbert creator Scott Adams joined Metafilter to defend himself in a forum criticizing him, but did so using a pseudonym. Scott Adams was outed very quickly by members in the forum, but Metafilter also confirmed it was Scott Adams after he refused to admit it himself.
A great overview explaining the various cultures and community mores that exist across the internet, just as all communities differ from each other. The best overview how complicated social can be in 6 minutes.