The Thieves Den

The Thieves Den (DLC7) is an upcoming official Bethesda plugin that will feature a pirate's lost ship and is designed for stealth-based characters. It will be US$1.89 for PC and 150 points on Xbox Live.

The description from the Official Oblivion Downloads page:
 * Uncover a famous pirate’s lost ship and claim it for your own. Designed for stealth-based characters.