Well, looks like Google PR now has officially commented:
Q: Just to make sure I understand, are you saying that pseudonymous Google+ profiles that are not associated in any way with a real name, but just use a game/online community/avatar account name, are not allowed?
A: Yes, we do ask for people to include the name they are commonly referred to in their Google profile. But we do have a field for them to enter a different name they are known as.
A: Again, Google Profiles are designed to be public pages on the web, which are used to help connect and find real people in the real world. By providing your common name, you will be assisting all people you know - friends, family members, classmates, co-workers, and other acquaintances - in finding and creating a connection with the the right person online.
Q: OK, so if I understand you correctly, you're saying that anyone with a pseudonymous Google profile should instead create one with their real name, and add their pseudonym(s) in the alternate field. Otherwise, they risk suspension. Let me know if I'm misunderstanding that.
A: Here is our Help Center article [http://www.google.com/support/profiles/bin/answer.py?answer=1228271
], which is best to reference.
Q: This link doesn't specifically answer my question. How does Google define "the name that you commonly go by in daily life"? Does that mean people who use an Internet community username in their daily life (in a social network, a forum, an online game, etc.) can use that name? For example, can someone who is well-known by their account name on YouTube use that?
A: Unfortunately, I cannot go into more detail aside from what's included on this site.