Mass Effect

This kind of leads me to believe that Mass Effect's DLC, slated for release on March 10th, is geared towards players who already finished at least one playthrough of the game.

Apparently the Bring down the Sky pack requires that players basically be at the point where they've received the Normandy and have access to the Galactic Map. According to Stephen Totilo, of MTVs Multiplayer blog:

Yesterday at the DICE summit in Las Vegas, BioWare co-founder Ray Muzyka confirmed to me that I would have to get my Commander Shepherd back in control of the Normandy spaceship — in other words, past the game’s opening Eden Prime and Citadel sequences — in order to access the new DLC.

It remains to be seen whether spare save games will counteract the need to play through the Eden Prime and Citadel portions so we'll have to wait it out. Thankfully I left off my second playthrough having just received the Normandy so hopefully I won't have to do much more work to enjoy the added portions.