Steam News announces the release of two pieces of DLC for Deus Ex: Human Revolution, the Explosive Mission Pack for $2.99 USD and the Tactical Enhancement Pack for $1.99 USD, which are both also available in a Tactical Enhancement + Explosive Mission Bundle for $3.99 USD (thanks nin). Here's word on what these add to the action/RPG prequel from Eidos Montreal:

Check out the Explosive Mission Pack to unlock a bonus mission, Grenade Launcher, Remote-Detonated Explosive Device and the Automatic Unlocking Device.

Or pickup the Tactical Enhancement Pack to unlock a Double-Barrel Shotgun, Silenced Sniper Rifle, and 10,000 extra in-game credits.