It's very easy to group your friends in different groups. Groups are like the ubiquitous "label", but for your friends. Group friends by degree (best, good, proxy, acquaintance, etc), or by classification (family, extended family, friends, professional), or even by interest (hiking, photography, school)
I have a lot of friends that I would like to keep up with, but I don't have time to. Some of these are old circles of friends from high school, or an old job, or my long distance best friends. I touched base with two different groups today, people that I really like, but haven't talked to or seen for months. Hangouts make this really easy. Hangouts are basically like private chatrooms with video meets social networking. I can foresee hangouts becoming incredible tools for all kinds of things:
Townhalls. I watched host the first townhall on Google+. If Google can really go to town with the Hangout technology, I can see the digital townhall becoming an incredible political tool. Imagine the power of being able to organize an actual town hall (moderation tools and all) for absolutely no cost.
Hangouts could also be chat rooms. A really good example already exists; User Plane. It's basically IRC meets Hangouts.
If posts become rich-text enabled with a WYSIWIG editor, the "Public" visibility option could become a good blog replacement.
With the Android phone application, it's also an excellent microblogging platform.
Google+ is a great new social tool, and if Google can play it's cards right, it could be the next killer social app.
Update: Actually, now that I think about it. Google+ is what Google Wave should have been.
Update 2: Circles are another powerful aspect of Google+. Now I can easily use the same social platform for my professional, and private faces. Google+ is a threat for Facebook and LinkedIn.
