To me the number's Facebook put out seem reasonable. I haven't seen evidence that Facebook's targeting capabilities have been yielding significantly higher CPC's for their ad network (and thus huge revenues). I've done some smaller buys, and yes you can control who views your ad on several grains (age, gender, location, etc.), however even with really great ad copy, CTR's are still surprisingly low given the boost you would expect from their targeting. They'll continue to refine their product but it still has a ways to go and targeting doesn't seem to be a huge competitive advantage at this point. I'd say that the big boost as of late (which was alluded to by other comments) was the loosening of their ad policies last year.

To the point about Yahoo, clearly they'll be less relevant going forward, but I don't think the comparison is completely fair. Keep in mind that they are still pretty much the king of display with an huge US reach (180MM Americans - http://www.comscore.com/Press_Events/Press_Releases/2010/1/c...).