Not that this is surprising but it appears rather then defacing sites outright attackers are now starting to target sites with adsense on them and replacing the codes in order to steal earnings. For those of you unfamiliar with adsense you stick a piece of javascript on your site with your code so if someone clicks it you earn money. The attacker is simply replacing the hacked website's affiliate code in their HTML with the attacker controlled code. Check out the forum link below for more details.

Forum Link: http://forums.digitalpoint.com/showthread.php?t=502683