Earlier this month, Facebook announced "Facebook Connect", which would allow you to sync Facebook accounts with other websites, such as Digg. With these developments came hinting that social networking was in for a change. Facebook has plans to veer away from being a normal standalone site.
Facebook hopes to bring it's application platform into open-source. Many other social networking websites are using "OpenSocial", a platform that any social networking site can use. Facebook has been one of the only networking websites that have disregarded open source.
But the question remains, especially given the scant detail of the latest rumor, about whether "open source" means truly open source or some variety of "extensible." Facebook has been redefining a whole lot of what we think about the Web, so this may be no exception.