When I got on the intertubes, oh-so-many years ago - the rules were simple: the ONLY piece of information you could freely give on public forums, or IRC, was your nick. Now, the only piece of information you are supposed to withhold is your credit card number. I'll say this about the new ways: I'm extremely glad that I didn't have my teenage years documented and archived. Dodged that bullet!
This made me much less reluctant to use my real name later on.
However, just as my real name, my pseudonym also stuck and I try to get it whenever I sign up for a service. That way I'm twitter.com/pilif, github.com/pilif, even facebook.com/pilif, though I don't use that.
Unfortunately, on G+, I can't be /pilif. I have to be pilif123459 or whatever. Too bad.