In their personal dealings? That's a pretty weird edge case. I can't think of anyone that does that besides con artists. (Dissidents, yes, but again, Google+ is for extending your personal identity; your alter ego belongs on a Facebook Page or Twitter or Blogspot or Wordpress).
>Twitter isn't primarily for alternate personas. Where did you get that idea?
Because Twitter accounts tend to be a way for organizations and celebrities to push information. Case in point: http://twitter.com/#!/paulg is about Paul Graham the entrepreneur, the professional persona, not Paul Graham the friend/son. I don't live in the Valley, but I have never encountered anyone with an active personal Twitter account. (Lots of people, including myself, made one, tweeted a few times, and gave up because nobody else we knew was there.)
To quote you: "I want to call people by the same name we use in person."
Unless I am dealing with a con artist, that is usually a real name. (Correct me if I'm wrong, but I don't think Google has an issue with normal first-name shortening/common nicknames). In what situations would someone be known to their friends and family by a pseudonym?