Its like an Ad in a hotmail email, the user is emailing someone not directly looking for anything, search is key.
Facebook listen! ok? You need a Facebook Search, then you got that advertising game! :)
Granted, a couple of those may be unfair. Facebook doesn't know my weight (though they do have my photo) and they probably wouldn't be able to data mine out that I don't drink. On the other hand, why are they trying to sell me a temp job when they know that I'm currently employed? Basic data mining should tell them that most of my social group doesn't have cable, so why are they trying to sell me a DVR? Plus, Facebook knows that I'm recently single and they couldn't think of anything to do with that? Or was that the tequila?
This is why I'm always surprised by the hubbub around facebook advertising. I actually get better targeted ads from the local newspaper. I guess Facebook's future just depends on which one of us is the anomaly.
You have just identified the next big thing in marketing: Parsing facebook pictures for ACTIVITY and PHYSICALITY of the people in the photos, then directing ads towards them based on the relevant info garnered from their photos.
If you have a bunch of pics of you RUNNING, SWIMMING, HIKING, SKIING, SNOWBOARDING etc... you can target that user base to sports ad companies.
Fat people get diet pills and other offers...
Facebook lacks that intent, so their CPC is always going to be quite a bit lower. Unless they can monetize intent. Every day there have to be millions of "can someone recommend a <blank>" status updates. That'd be an ad I'd be interested in buying.