Valve have revealed that the new DLC for Left for Dead, named The Passing, will be released this week via Xbox LIVE for 560 MS Points.
The new content bridges the Gap between L4D and L4D2, seeing the survivors of the original meeting up with the new guys and allowing users to play through the games three new maps with new weapons causing yet more zombie smashing.
You can check out more information on the game over at the Left4Dead Blog.