Some people have asked me about Google + and how it fits into the scheme of things. While it isn’t quite mainstream yet, as far as third party apps and convenient posting, it is getting very popular. (by mainstream I mean I can’t automagically post to it from Hootsuite)
The key to the differences is the direction of the relationship and how you interact with folks.
Facebook: You and I are going to see each other’s posts.
Twitter: I want to see your posts. Look at mine if you want.
Google: I’m going to share my posts with you. Share yours if you want.
Of course they all have various privacy settings that vary in different ways. That’s too much to go into here, I just wanted to put up these three paradigms as food for thought.