DLC for Dungeon Siege III has been outed via Steam after tech-wizards poked around inside the service using third-party software. RPGSite inadvertently discovered the packs when looking for Final Fantasy VII and VIII on the service, though it was Joystiq that picked up on the leak.
A list of current and upcoming games and DLC can be found under the ClientRegistry.blob file, which is where the DLC was outed. Burning Band of Scorch, Talisman of the Grand Mage, Bite of the Arakun, Sacred Heart of the Legion, Annulus of Force and the Medallion of St. Elys, all previously pre-order exclusives, were all listed.
This suggests that all the packs will be released on Steam at some point, with XBLA and PSN likely joining them.