Social networks remind me a bit of webmail back in its heyday. Microsoft paid hundreds of millions for Hotmail only to realize that it was hard to monetize because people go there to look at emails, not ads.
If you search for "luxury car" on google and see ads for BMW and Mercedes, that's useful to you because that's what you were looking for. But ads on the side of your social feed on facebook?
Some will argue that they can be very targeted because of all the info that Facebook has on you, but it still doesn't change the fact that you're not looking to buy stuff, and even if you are, there's no clear way to signal that intention like with search. Then that leaves more "branding" type of ads, but those are a lot less valuable and effective, and can easily be ignore because they're not showing something you are looking for at that moment.
Then they'll probably try to keep pushing further the whole "your company needs a strong presence on FB with a brand page", but how valuable is that? Good way to communicate with your customers and remind them about you, but if I'm looking for info on a BMW, will I go to BMW's FB page or to their official website? And even if I go to the FB page, will any info be there? Is the company going to re-build their whole website on a platform they don't control, or just throw you to the existing site with a link? So how much can FB charge for these brand pages?
Then maybe they'd decide to pull a Google and go into search and syndicated ads via an exchange, but what are the chances of success there? Even partnering with Microsoft - who has only lost billions on search and ads so far - would what FB has really be some secret sauce to take search to the next level? Is all the crap that people post on FB really the way to make search better for users or will it just clutter up results with junk? I'm sure advertisers would love better demographics info, but it's the user experience that makes web tools succeed or not.. We'll see.
/thinking out loud
I don't have a horse in this race anymore, though. I made about 25% in GOOG in a month and then sold it to buy something more undervalued... It was luck that it turned out that way, but I still believe GOOG should do well over time, though it isn't nearly as cheap now as it was at 475.