Awakening takes place after the (many) events of Origins, putting the player in the role of a new Grey Warden Commander, or simply an old, imported character from the main game, taking on new monsters, like the Inferno Golem and the Spectral Dragon, in a new area of the world called Amaranthine. The expansion features an increased level cap, new items, new spells, the ability to "re-spec" attributes, and five new party members with whom to bond.
It seems odd that the DLC delay and the expansion announcements would coincide so closely, though we don't think it's a matter of BioWare trying to starve people for Dragon Age content so that the expansion would appear more attractive. We can't think of any other explanation than "it's a weird coincidence," though we'll attempt to clear it up with BioWare.
Update: Check out the debut trailer.