Google + had to be shut down due to too much demand on the piolet project. The Google team was supposed to hand out only a few beta trials, each allowing the user to send an invite to 15 people. Well the Google team got a little excited and began sending out invites all over the friggin place.
The result is one of the best PR schemes in a long time. Google can now say “It’s so good we just couldn’t handle the demand, like the Wii.”