The bottom line is that social networks are mostly a waste of time. Geek and Social do not really go together. You usually have a small and close group of friends and you sure do not need FB or MSp to connect with them. I have a FB profile and that is because I have a Facebook application and my only friends are a few users and my co-foundrs. But remember that just because you are not using Facebook does not mean you should not look for opportunities in the environment. If you can build an app that will generate a nice return within a few months, then do it.