Another issue with Facebook is that content is created for consumption by all of your connections. It's social preening. It's what you aspire to be, but wholly incomplete as a medium for search.

A few of the missing items:

-All the dirty stuff you won't show your grandmother. "Watch what you post" is part of raising kids today.

-What you fear. Do you post that you need an abortion or that you might have cancer?

-Gross stuff. Nobody posts that they have hemorrhoids. Or any number of things that you don't want girls you might date to see.

-Things we're ashamed of.

-Things that make us different. If you're a gun-toting neanderthal in SF or a gay man in the bible belt, you might not want everyone on facebook knowing that.

-Things the government will read. Reading revolutionary ideas, means of destruction, might be interesting and educational. However, posting on these topics or having a traceable record of them is a wholly different level. Think about prosecutorial misconduct.

I think FB will have a reasonable degree of success in search. However, it's badly gimped.