Ok, I'm biased because I'm a search guy but for some reason I get more creeped out by people inventing new ways to track down other people than I do about people inventing new ways to connect someone to a product sale.
We've heard from people trying hard not to be found because it doesn't "add value" to them if that person some high school they had such issues with lost track of them.
I certainly agree though that the information Facebook has could really inform a search product. We (Blekko) did an experiment using Facebook likes from your friends to inform results rank. The results were pretty cool when you searched for a seafood restaurant in SF and the result said "250 of your friends like this place." That can give you a sense that people you know (and possibly invest a bit more value in their opinion :-) thought this restaurant was good, as opposed to people on Yelp who you do not generally know.
We've heard from people trying hard not to be found because it doesn't "add value" to them if that person some high school they had such issues with lost track of them.
I certainly agree though that the information Facebook has could really inform a search product. We (Blekko) did an experiment using Facebook likes from your friends to inform results rank. The results were pretty cool when you searched for a seafood restaurant in SF and the result said "250 of your friends like this place." That can give you a sense that people you know (and possibly invest a bit more value in their opinion :-) thought this restaurant was good, as opposed to people on Yelp who you do not generally know.