It's been reported that two new API methods for Facebook are in the works, both revolving around how friends are handled and organized within the Facebook networks.
The two API methods are entitled friends.getLists and friends.getListsMembers. While the precise specifications for these new methods have not been revealed, it could be speculated that these could let you organize your own distinct circle of friends, for various purposes. Other important points that have been brought up include the affect this could have on privacy controls, perhaps when it comes to Facebook applications. Could several versions of your Facebook profile be available to different people? As a major drawback of Facebook applications is the inability to display private applications on your own profile, the implications of these upcoming API methods could address these privacy issues.
As LinkedIn is a niche network for business professionals and is also gearing up to launch its own platform, and Slide's Top Friends Facebook application has remained amongst the most popular, Facebook's new APIs have been noted as potential threats to both of these other networks.
Whatever the case may be, we're certainly seeing a shift for social networks to help users distinguish amongst their many reasons for creating an online presence, and offering ways to use a single profile for multiple "sides" of a person. CollectiveX, Groovr and Friendster are some networks that are offering tools for just this purpose.