Many non-Americans ask why the final competition of champions in Major League Baseball each year is called the World Series when it is only for North American teams. Wikipedia debunks the myth of an originating sponsorship by some company called World's Almanac -- apparently, the originators really did believe they would be crowning the world's best team at the end of this contest.
In that spirit (and since the World Series is nearly upon us, as all good Red Sox fans know), I offer a World Series of Social Networking between LinkedIn and FaceBook. I happily ignore MySpace (huge) and everything else (small, medium and large) in the space for the really important reason that I am active only on these two sites.
With LinkedIn you can see where your professional contacts are now, find them pretty easily, and connect to others through a chain of trusted connections. There are other features, but these are the valuable ones (in my mind) because they foster and utilize professional trust relationships in a unique way. Facebook allows you to share your news and thoughts and other data with your friends in a fun, easy way. Doing so with professional colleagues can be interesting, but there are certain aspects of my colleagues' lives and thoughts in which I am just not interested (their sports predilections, for example). I imagine their view of my Facebook life, mostly aimed at family and friends, is even dimmer!
So I find that Facebook is a much more compelling platform for me personally right now, but LinkedIn is more suitable for professional work. My personal and professional lives overlap significantly, and I do not really want to maintain two separate networks (one for friends, one for work colleagues). With this in mind, I was happy to read this analysis from Techcrunch that Facebook is now adding features that target the LinkedIn demographic. If Facebook pulls this off, and perhaps even offers a way to import LinkedIn profiles, it will be a really interesting move. It will take a considerable effort to duplicate the complete LinkedIn network on Facebook (perhaps only possible with an acquisition), but it could happen over time. The notion of Facebook allowing me to group friends so that they see different aspects of my life makes lots of sense. Keeping active on both is a pain (Facebook is winning the attention-share war in my case).
I think this is at least a best-of-seven-games series, and there are many more games to play, and all to play for.