Rockstar's sent out an update to the Xbox 360 version of Grand Theft Auto IV to add in the Achievements for the upcoming Ballad of Gay Tony DLC.
All you need to do is stick in GTA IV into the trey, boot it up, update and bam. Gamerscore for the game now bumped up to 1500 from 1250.
More info over at StickSkills.
The Ballad of Gay Tony is out on October 29 on Xbox Live and at retail with Episodes from Liberty City alongside The Lost and Damned.