Google+ is an ongoing project, and it's not complete at all. So far, Google has revealed several key concepts that play a central role in their social networking thing, and they claim to be trying "to bring the nuance and richness of real-life sharing to software". The four key concepts are Circles, Sparks, Hangouts, and Mobile.
There's a lot of words in Google's announcement to describe what are basically groups of contacts. Google thinks that sharing and social networking today is too crude, and that it's kind of odd how you are forced to share everything with everyone in your list of friends - including your parents or your boss. Circles is supposed to change this.
Sparks are Google's equivalent of Facebook pages (well, sort of - okay, actually they're not). You can create a lists of interests, and for each interest, interesting content will be served yo you - photos, stories, videos, whatever. You can then share these with you friends or circles. Any topic, in 40 languages. Pretty cool.
I kinda like the idea behind Hangouts. "With Google+ we wanted to make on-screen gatherings fun, fluid and serendipitous, so we created Hangouts," Google writes, "By combining the casual meetup with live multi-person video, Hangouts lets you stop by when you're free, and spend time with your Circles. Face-to-face-to-face."
Mobile is just that - mobile. It's about easily sharing photos and such, location stuff, and so on. Huddle is also part of this; it allows you to easily get people together in real life. Considering I bang my head on my desk a few times a month whenever my friends and I are trying to get together, this could be interesting.
As always with Google, this stuff is in beta, and invite-only at this point. We'll see if it sticks.