There is a famous cartoon dating from the early days of the internet with the tag "on the Internet no one knows you're a dog". This is true but total anonymity is rather harder than people think and will, I believe get much harder. Perhaps more to the point the anonymity of a particular nickname becomes much harder the more you comment, post etc. using it. Likewise once your name and contact details are exposed anywhere on the internet people will abuse them - usually to send you messages about "v!@gr@" - but sometimes to send you hate mail, and privacy is like virginity, once you've lost it you can't get it back.
For example many lefties have reacted in variousdegrees of outrage at Michelle Malkin's publication of the contact details of some clueless UCSC students who put out a press-release of particular imbecility and then wondered why they got hatemail. Now I don't think people should send hatemail, but I am afraid that it seems to be a demonstrable fact that there are idiots of all political stripes who like sending nasty emails to people who take positions they disagree with and if they have other personal details they may also use them too. Now it seems the lefties have exposed Michelle's home address etc. Unlike some who react to that withcondemnation, I react more with resignation.
In all such cases, if you know someone's real name and some basic facts about them it is ridiculously easy to find out the rest so if you publish your real name then you can expect someone to figure out the rest even if you try to obscure it. Publicizing that information without their permission is, arguably, crass and rude, but it isn't an invasion of privacy or anything else. Although I am a little bit embarrassed to mention this I frequently use a variety of tricks to send email to people that I think might be interested in the company I work for or something similar, but who don't publish their email addresses obviously. It is not difficult to do and while, it isn't foolproof, I reckon I have a hit rate of 90%+ for a technique that involves about three google queries. In the 10% or so where that is not sufficient a few more queries and possibly one or two phone calls are all that is required and I don't think I have yet failed to get the email address eventually.
This also means, to get back to my original point, that coming up with anonymous/pseudonymous alter egos that you wish to keep separate from your "official" on-line (or offline) identity requires a certain amount of care and attention if you wish to keep them separate. The critical thing to remember is that when you post a comment, your IP address, email address (and sometimes some other details) are generally stored along with whatever comment you made and the pseudonym you used. For example if you post at the same blog (or related blogs) with different pseudonyms but the same underlying IP address(es) then, if the blog owner cares he can identify that you are one and the same person, and may decide to publicise this.
Personally I am all in favour of this. To me anonymity is generally speaking bad, which is why I'm not at all in favour of anonymous leaks, and why I was able to approve Mr Galloway's exposure of Mazher "fake sheikh" Mahmood. I think that except in cases where lives or livelihoods are in clear danger from retaliation we do better not having anonymity. I believe that the one thing the Internet is doing is helping people to make their own decisions about the credibility of others and that credibility is significantly helped if you can identify the person behind the remark. This BTW also means that I agree with Jeff Jarvis's comments about journalistic (and blogger) disclosure.
Slightly off topic: On this general subject, but more for blog-owners than commenters, I do think that this advice at RightWingNews is good and needs greater prominence.
Disclosure: At various places I use the nickname "Dirty Dingus" for reasons of primarily historical interest. I probably could change Dirty Dingus to my own name but why bother? I don't care and I can't see that it hurts anyone to do the necessary back tracking to figure out that Dirty Dingus is me.
Update: Mr Hiltzik makes a lame defence. All I can suggest after reading that defence is that Mr Hiltzik head here