Seems like Pitch Tag has really taken off on Google Plus! Here are some ongoing threads.
» Jared Axelrod
» Dev Purkayastha
» Brett Myers
I can already see the challenge of playing Pitch Tag on this channel, though. As the thread ages, it draws fewer new participants to add new life. Eventually the thread fades when the current participants burn out. Granted, that'll happen regardless of the channel, but it seems to happen faster on +.