On PC, Mass Effect will include Bring Down the Sky and Pinnacle Station on disk. For Mass Effect 2, Cerberus Network will be included which features Zaeed – The Price of Revenge, The Firewalker Pack, Cerberus Assault Gear, Arc Projector heavy weapon, and Normandy Crash site mission. For Mass Effect 3, Online Pass will be included granting players access to co-op multiplayer.
On Xbox 360, Bring Down the Sky and Pinnacle Station are not included with Mass Effect, however they are available as stand-alone downloads through Xbox LIVE. For Mass Effect 2, Cerberus Network will be included and Online Pass will be included for Mass Effect 3.
Information on PlayStation 3 DLC will be available soon.
Considering that at least a couple of the Mass Effect 2 DLC packs released ties into Mass Effect 3's plot, I would have expected the folks at BioWare to include them in the package.