It didn't take long for anonymity on the Internet to become a contentious issue, and for good reason. Anonymity is problematic.
It is usually possible, even easy, for users on the Internet to hide their true identities to a degree. Most Internet protocols have weak or no authentication in them and it's usually not too hard to keep your real name from other services, like social networking sites or blog comments.
There are all manner of good and bad reasons for doing this. The good reasons, expounded well in the EFF's (Electronic Freedom Foundation) brief on anonymity include protecting the identity of those engaging in controversial political speech.