Google announced today that an administrative managed version of Google plus is coming to businesses and educational accounts. I don't think this means it is allowed in k12 yet but I hope that k12 integration will soon follow.
Bjorn Behrendt M.Ed ~ Never Stop Learning
Google Apps For Education Certified Trainer
~ Google Weekly ~ 40: Hangout Baby Monitor (8/12/2012)
~ Teaching Change ~ 3: Transferring Google Docs (6/4/2012)
~ AskBj.net ~ Online Training and Ed Tech Resources
~ VTed.org ~ Vermont's Personal Learning Network