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.
The founding fathers were serial anonymists. They wrote constantly for public consumption under pseudonyms, I suspect because personal attack in public debate was an even greater problem then than it is now. Taking one's name off an argument leaves just the argument.
Any student of American history knows of The Federalist Papers, essays written in 1788 and 1789 in support of the proposed US constitution, and especially for the ratification debate in New York. They were written by Alexander Hamilton, James Madison and John Jay under the name Publius. Anti-Federalists wrote their own anonymous arguments under the names Cato and Brutus.
Unlike speech, anonymity on the Internet isn't free. Not everyone's Publius these days, so a lot of speech isn't just free, it's cheap. And while Hamilton must have paid for the publication of the Federalist Papers, When you write something anonymously on Blogger or MySpace you are doing so as a user on their system and you have agreed to follow their rules. As our Jim Rapoza has pointed out, violating these terms, even just by providing a fake e-mail address, can put you in legal jeopardy, as it did the defendant in the MySpace suicide case who was convicted for creating a fake profile.
Unlike Jim, I'm not comfortable saying that we have a right to violate Internet services' terms of service. I say that if you don't like the terms of service, don't use the service. Abusive people often hide behind anonymity to intrude on the privacy and rights of others, so services often need to insist in real identities. That's one thing, and it's another to say that violating those terms violates a Federal law.
As a policy matter it's reasonable to be concerned about anonymity. As Esther Dyson said in a recent interview "...it turns out anonymity really encourages bad behavior." She sees it as a right, but a corrosive force, at least in many cases. She's right. I would also point out that to me, anonymity is somewhat synonymous with weak authentication, and that weak authentication is comorbid with pretty much the full range of Internet security problems, from spam to botnets.