This will be the third expansion pack, not the first. The first two were the Stone Prisoner and the Warden's Keep - I think they've been available for download since the game launched.
Mass Effect 2 may have me forgetting all about DA:O by the time this comes out... I feel like I've hardly scratched the surface on that behemoth of a game. Still, it would have been cooler as DLC a la GTAiv.
@ Reymont: Under the traditional definition of the term "expansion" I'd agree, but according to all the official info from EA everything released prior to Awakening is merely "downloadable content." Thus, through idiot logic, Awakening is the first official expansion.
And the game always contained dragons...