The same sort of thing will happen as software becomes more social. Lots of people think "social" means "social networking." Sometimes it does, but the larger point is that collaboration and history are the key elements of a "social" application. Rankings, ratings, reviews, visits, "likes," bookmarks and retweets are some of the ways people indicate that something is valuable, useful or interesting. It is annotation of the real world.
And that's the important thing about location and social. Mobile happens to be important because the mobile device is both a sensor and a display that always is with a person, allowing the annotation to be activated.