ONE OF THE most interesting things about Google Plus is the way I've seen it used in business when conducting close-held discussions. G+ lets you keep things from prying eyes.
Most people look at Google Plus as an alternative social network, but knowing they don't have the time or energy to relocate themselves and their friends from Twitter, Facebook, or Pinterest. Even though some business strategists (like David Armano with his graphic) see G+ tying together communications, collaboration, search and media, few people point out how there's an invisible pillar in the G+ schema. It operates behind the scenes and goes largely unappreciated by social media experts. It's the locked-down and private channel for collaboration.
If you trust Google Docs as a channel for communicating only between your business partners and if you use Google Forms to capture data without it leaking across the internet, you're familiar with the plumbing on the private side of Google Plus.
I've seen this plumbing working to great effect during private Google Hangouts too. I can get RSS feeds from blocked Google accounts--information I can see when passing credentials through Google Reader--those blog posts, link lists and discussion threads I can harvest are ones that others don't see when they look up a person on Google Plus.
To keep something totally out of view, you need to ensure everything you post is constrained via the "lock this post" command. You also should know that merely "blocking" someone does not prevent them from seeing (and grabbing links) to your posts.
I follow people on both Twitter and G+ via RSS feeds when they've blocked me from viewing their content on the main websites. They won't see me or my content unless I communicate via one of my alter egos. If they wanted to completely block me from accessing content, they would need to lock down their entire account ("protected" on Twitter and "share" only to a circle containing just themselves.
I've used a dummy account on G+ as a private diary. It's remarkably quiet, totally cloaked, undiscoverable, and unsubscribeable. For Google to offer this facility is quite remarkable, considering the amount of flak the company gets for pushing the edge of the privacy envelope.