Bethesda confirmed at a recent press event that Shivering Isles will be one of the first games to make use of the extra 250 achievement points available for downloadable expansion packs.
The Oblivion add-on for 360 will also feature new shader technology that should bring the game up to the graphical standard of the PS3 copy, adding to recent comments from Bethesda spokesperson Pete Hines that the two versions will look virtually identical.
Shivering Isles is the first proper expansion pack for the The Elder Scrolls IV: Oblivion. It takes place in the wacky realm of Daedra Prince Sheogorath, who looks to you to become his champion and save his world from invasion. You'll be tasked to undergo lots of weird and wonderful quests, picking up new items, spells, and crafting new armour.
It's due for release in spring, via Xbox Live for console owners, and in retail stores for PC pests.
Oblivion is a launch title for PS3 when the console arrives in Europe on 23rd March. There's no word on the inclusion of the expansion pack, though previous downloadable update, The Knights of the Nine, will be included.
Head over to our first impressions of the expansion pack, which are loitering in other realms of our website