Google+ this week rolled out a new security feature for the organizations intended to make sure that private conversations remain private from the larger web. More likely "Microsoft's Yammer" where Google+ communities will only allow to access the approved stuffs. Whether it’s designs of your beta product or notes from your team off-site, anything you post will remain restricted to the organization. Community administrators can decide whether the site will be open to everyone at the company or it could be kept private and joinable by invitation only. So overall controls permit the administrators to restrict the communities as default for their organizations. Also you can choose to create communities open to people outside of your domain, so clients, agencies or business partners can join in the discussion; all are hassle free!