As reported, Google+ has decided to ban the use of pseudonyms as well as nicknames in place of real names. (August 12th, 2011 | http://en.inmoreau.com/862)

The new Profile Verification Badges help you confirm your authenticity. For now, verification badges are only available to public figures, celebrities, and people who have been added to a large number of circles.

(from Channel of googleplus)