So here's a thought. I was just reading some of the comments on this Slashdot article about some ridiculous new buzzword called “geomicroblogging” (think Twitter linked to your GPS coordinates). It occurred to me that the future of social networking sites will have to involve discrete groups that you can assign people to.
Currently, these sites lump everyone you know into a single category, your “friends”. The problem is that in real life, that's not how we associate with people. We have actual friends, we have family members, we have coworkers or bosses or subordinates, we have classmates or teachers or students, and we have people we know only through online forums, chatrooms, and games such as MMORPGs. We may not consciously treat members of these different groups differently - one might say to oneself, “I am me, and everyone around me sees me as me.” Still, chances are there are details of your life you don't mind discussing with certain people, that you'd rather not discuss with certain other people.
One example that comes to mind is a friend who chose to restrict certain postings on her blog to be visible only to people she considers to be “friends”, which excludes most of her coworkers. Many of these postings were of a very personal nature that she was comfortable sharing with her friends, but didn't want anyone else to read. Another example is a woman I know who works as an “escort” - she has a web site advertising her services to the general public, but it's not something she would want her family or casual acquaintances to be aware of. I work with a group of students and need a convenient way to stay in touch with them and their parents, but they don't need to know any details about my personal life such as my religious background or whether I'm bringing a date to the party I'm going to this weekend.
An example somebody gave in response to the aforementioned Slashdot article was a woman who added her nieces and nephews as “friends” on Facebook, and now knows exactly when one of her nieces lost her virginity. Obviously it can be argued that parents have a right to know these things about their own children, but since the children don't want to share this information with their parents (while still sharing it with the rest of their peers), social networking sites will have to change to meet new demands.
I expecct this shift will start by allowing users to select different groups to put their friends in, and more fine-grained control over which groups have what access - for example, I might choose to post a photo of me sampling some rather interesting 160-proof rum at a party two weeks ago, but hide that particular photo from people I go to church with (I don't have a problem with it but would want to avoid any issues).
I'm sure eventually somebody will figure out how to make this process seem natural rather than technical, but at first it will require quite a bit of sophistication on the part of the users. It's a lot easier to just post things for all the world to see, or restrict all access to one particular group of people, but as users become more and more familiar with the Internet and social networking sites, I think a fine-grained approach is becoming quite reasonable. The question is, will existing sites like MySpace, Facebook and LiveJournal adapt to offer these new features, or will they be replaced by new sites that do?