Console Monster writes: "We have just added the new Achievements for Mass Effect on the Xbox 360. The achievements have appeared to come out of the blue.
The achievements relate to a new survival mission titled "Ahern's" which looks set to be the next downloadable content for the title. The mission is set to take place on Pinnacle Station, where players will be able to place in combat scenarios.
The 3 new achievements are worth 150 GamerScore. The release date for the DLC is unknown, those these achievements suggest we'll be seeing it sooner than we think.
The list now contains 49 achievements worth 1200 GamerScore..."