[EGreg]

This is what Overture was doing for advertisers back in the day - relevance based on payment

then Google came along and made pagerank -- so relevance was actually based on relevance and not just ads

but then it acquired overture's patents and made the adwords, which is back to paying if you want to be on top

So I see the same game playing out all over again. Facebook can be the overture and we will be the google :)