The facebook platform is emerging as a must know skill set for social development. Facebook is evolving from just a site for social networking in to a platform which will allow companies to create applications for Facebook and to bring the facebook Social Graph in to their applications.
The goal is that in the future facebook could be Cloud platform like Azure, but one that puts the Social central to all applications. This will require an entirely new way of thinking about computing. Rather than seeing a user facing a machine that connects to devices and interfaces, developers on a social platform will need to think of any one person as a member of a community with its own complex history and patterns of interaction. Software will be more like creating folk cultural forms rather than singular pieces.
To use a tired term facebook aims at a kind of "global village" where programmers will be more like tribal leaders producing forms to be used and re-used by the community, rather than like say movies or video games which are produced by a firm and consumed in a set way by the audience.
So far most of the movement towards social platforms have been to extend existing machine to person platforms to include a community element. For example XBox can be extended to XBox Live. There have been some noteworthy platforms that are fully social like Second Life, but nothing has ever had the reach or ambition of facebook's platform.
Right now its all pretty basic. Almost everyone has a faecbook likes links on their blogs and many sites have a iframe to their facebook site, but it very soon could become far far more complex.