The new Cold Stream DLC, which includes a fan made campaign and versions of the original Left 4 Dead’s campaigns will arrive on the 24th July. Cold Stream will be available for Xbox 360, Mac, and PC.
The following campaigns from Left 4 Dead: Death Toll, Dead Air, Blood Harvest, and Crash Course will now be playable with the Left 4 Dead 2’s characters, weapons and various other improvements such as more varied infected.
I am pretty sure it will be free for PC and Mac but Xbox 360 users will likely have to pay for it if their previous DLC is anything to go by. In 2010 their previous DLC The Sacrifice had to be paid for on Xbox 360 while free on PC.
From l4d.com “The Sacrifice will be available as two separate packages on Xbox Live for 560 Microsoft Points each and free to all PC gamers.”
Which will likely be the tactic this time too. Whatever the case its good to see them updating the game even it makes the orignal even more obsolete than before. However the orignal has the better characters. Poor Bill.