Citing "the presence of a locked out art-file or 'skin' that, if accessed through a third party modification to the PC version of the game, allows users to play with topless versions of female characters" the ESRB has elected to re-rate Elder Scrolls IV: Oblivion raising the rating from Teen to Mature.
http://www.1up.com/do/newsStory?cId=3150264
Not that this affects me in any way, but it's just like the whole GTA:SA fiasco.