"If you currently have a private profile but you do not wish to make your profile public, you can delete your profile. Or, you can simply do nothing. All private profiles will be deleted after July 31, 2011."
That only stops Google+ internal search from returning your profile given your name. Your page is still public (and linked to by, for example, your friends' pages) so any search engine can index it.
http://www.google.com/support/profiles/bin/answer.py?hl=en&#... http://news.ycombinator.com/item?id=2321727