You make a good point. I imagine (very much a guess on my part) that Google would prefer to have eyeballs on their own impressions of adsense than those on oth

You make a good point. I imagine (very much a guess on my part) that Google would prefer to have eyeballs on their own impressions of adsense than those on other sites though -- because there would be no payout in those cases. Still, I would think that serving ad impressions on 3rd party sites is likely a large part of their current business. Maybe those are just eyeballs they rent as appose to own then. ;)