Technically speaking it could go in any of the 3 areas(PC, 360, PS3) seeing as how it's been released on all 3 platforms. But I personally think it should go in the PC area because it's essentially a PC game that just happened to also be adapted for both the consoles.
And I also might add the description for this area...
Not only is Oblivion not exclusive to the PS3 but it was released almost half a year after the PC and 360 versions.
But rule discussion side, Oblivion is a very good game.
I have a friend that started to steal stuff from the guilds (Mage, Fighters, etc), he literally cleaned the place up, I think he stole even the kitchen sink.
Needless to say, he got rich pretty fast that way.