It's true that FB hasn't found a way to convert the time spent on it to revenue the way google has, but facebook will still make a lot of money selling targeted display ads in the short term. They'll do this while stealing market share from content companies like Yahoo, AOL, etc.
The money from display ads will give facebook a lot of money and time to come up with a better way to market using the social data they have.
The money from display ads will give facebook a lot of money and time to come up with a better way to market using the social data they have.