The Google+ Project or Google Circles launched on 28th June, 2011.
|Google+ is an essential part of my business, with other Google tools.|
They've come a long way since.
From the official Google blog announcing the launch, written by +Vic Gundotra:
+You: putting you first, all across GoogleThat’s the Google+ project so far: Circles, Sparks, Hangouts and mobile. We’re beginning in Field Trial, so you may find some rough edges, and the project is by invitation only. But online sharing needs a serious re-think, so it’s time we got started. There’s just one more thing—really the only thing: You.