Oblivion is getting a Game-of-the-Year edition for PC, PS3, and Xbox 360, which will include the Knights of the Nine DLC and the Shivering Isles expansion pack all together.
The two pieces of content are currently available on the Xbox 360 and PC, but Shivering Isles is not available the PS3. We still wish that it was downloadable for the PS3 because this means current owners will have to purchase the game again to get the expansion.
The GOTY edition will allow players to pick up where they left off if they have a save file from a previous version of Oblivion and newcomers will get some extra content off the bat.
Seriously, PS3, get your DLC act together. It's the way of the future.