Irrational Games has announced previously that BioShock Infinite will be receiving three DLC packs sometime in the future. In recent interviews Ken Levine has said that the development team had just started to plan what the DLC is going to be, indicating that any DLC for BioShock Infinite is probably a ways out.
However, a reader for another site found indications that BioShock DLC might not be as far out as originally thought. A Steam BioShock Infinite Achievement community page lists ten new achievements for the game. You can see the image below or go to the official site to see the entire list here.
There are no descriptions attached to the ten achievements, so there are no hints or indications on what the DLC might contain. Although we still have no idea what the DLC might be, this find does indicate that Irrational Games might be further along in the process of creating the content than we expected; which hopefully means we will be getting BioShock Infinite DLC sooner rather than later.