the thing is, there is at least a 33% chance that with facebook's lock in, millions of site integrations, virtual currency, the coming smartphone boom, display network, developer platform, and all the other shit they are doing, they could end up worth more than google. So I really can't say that valuation is unrealistic, cause for all we know it could end up low when they go public. They do have 2 billion a year in revenue, and they haven't scratched the surface of what they can do with social ads.