So in what way do you suggest Facebook will generate revenue? Do you think we will have to look at ads before we view people's profiles? Ads before we view videos with ads on? How about pay to promote your own posts? The latter its already being trialled. There is not much Facebook can do to generate revenue that would not irate its user base. You can skip most YouTube ads after 5 seconds; embedded videos don't normal have pre adverts, just adwords.
100 times revenue, let alone profit, is far inflated to the point of fantasy more than common sense. Google is not a very good base to judge Facebook's value, as it also over valued but has the benefit of having its core business so widespread. Common investment principles don't seem to work with many internet IPOs: it's like the hype on games like Dragon Age 2; it's over priced, poor value for moneyand something you probably should have listened to your gut rather than the kid with BO whose only views on games come from a games magazine.
No doubt Facebook's value will be stable because it's a cool share, just like Apple and Google, but fashions change.