The Google+ social network has been integrated seamlessly into services like Google search, YouTube, Gmail, Google Drive, etc. Today Google+ will be integrated into Google Groups into a new set of “Communities.” Google+ Communities lets anyone interact publicly or privately about all sorts of topics like cars, fashion, cooking, astronomy, photography, etc. Google+ Communities lets you start hangouts and plans events with other community members.
You can try out the service by clicking on the Communities icon on Google+. From there you can create or a join a community.