Based on Ratios, FB at $38 is like 10x more valuable than Google. But as I mentioned to Wayne earlier, people use Google almost all the time when they are either thinking of, or actually buying something. Facebook ads are more like TV ads, just random noise that gets lucky once in a while. Other than being more targeted based on demographics I don't see it. Actually literally I don't see it as I use adblocker and have been for years so I keep forgetting the internet is flooded with banner ads. Don't know why the vast majority of people don't install one of these plugins, they are dead simple.
Plus more and more people use FB on their phone and there is very little room, especially at 3g speeds, for intrusive ads.