Sandberg was a good part of the "business" side of Google's rise to being the most important company on the web. If Facebook has also managed to hire someone who can come up with an AdWords-style technology that makes all of those eyeballs staring at Facebook worth more than a few pennies each, Facebook might eventually be worth some of the hype.<p>I've never met Sheryl but I know a lot of the folks that worked directly under her at Google, and they were universally in awe...so, she's probably just the right kind of grownup Zuckerberg needs to have around.
The problem with the social network is that it's more personal than search. Search, while personal, can be made innocuous by keeping annonymous information.<p>The holy grail of the social graph is to find out who the viral supernodes are. By that measure it's no surprise they went straight for the purchase history. If you can pinpoint the people who most influence other people you've got the potential for a very powerful statistic which can be fed into a viral marketing campaign.
I can't trust any article that says Microsoft's investment gave Facebook a valuation of $15 billion. It wasn't a pure investment: an ad deal was part of it.