L4D2 SDK Released!

Just released today for the Holidays is the new L4D2 SDK; you can find it under the 'tools' tab on your Steam window.

L4D Blog said:
PLAYERS: If you are not looking to design but play custom campaigns all you need to do is install the add-on support package. Just go into steam and open up the Tools tab. Look for the entry labeled Left 4 Dead 2 - Add-on Support click and install it. This download is sizable, but will update your L4D2 installation to allow running ANY map, including custom maps made for the original Left 4 Dead. Once installed, you do not need to run this application, it will always be active.

We will be updating the Left 4 Dead 2 game UI to include links to this package when applicable but for now please just download it directly. If you see any missing textures or models from your favorite map let us know in the forums.

Find out how to get it, and read more at the L4D Blog

The SnarkPit has also been updated with a database entry for your new L4D2 maps too! Apparently porting your original L4D map to L4D2 is pretty easy as well. Time to get mapping on your new L4D2 maps!