Offical Playstation Magazine confimed that the rumors about Oblivion being a launch title on the PS3 were true. The game has extra added content, such as a new faction available from the start called 'The Knights of the Nine'. The quest for this faction has you becoming a Divine Crusader (which is essentially a paladin) and features new locations, weapons, characters and armour.
Executive Todd Howard spoke about the new content, "Oblivion has these really good character archetypes for evil, It has the Dark Brotherhood: You get your outfit, you feel like an assassin, you feel like an evil guy, [and] you role-play like an evil guy. We [didn't] have the opposite end of that. There [was] very little reward for being a goody two-shoes."
"As opposed to adding content that allowed your character to just experience new quests, we wanted to create something that allowed your character to become something new."
It has not yet been confirmed if the extra content will be available on the Xbox Live Marketplace, however, that's a likely possibility.
Elder Scrolls Travels: Oblivion plays in a similar way to Elder Scrolls IV, but has a completely different environment. Little else has been revealed about the PSP game so far.