Valve recently announced the delay of the Left 4 Dead 2 SDK, much to the dismay of the many modders out there in the L4D2 community waiting to get their hands on this development kit. However, news regarding the capabilities of this SDK has been released, which managed to alleviate some of the disappointment that they felt. This kit will support custom infected, survivors, weapons and more.
Custom models are supported and this has been confirmed by a group who managed to give it a test run. Special infected, survivors, weapons are all able to be customized now. The weapon functionality can also be altered, which means that you can have custom survivors, special and common infected and new weapons particularly formatted to your campaign. This is nearing the power given when giving you are aiming to do a total overhaul, or make a game based of another games engine. These capabilities will now require the modding community to raise the standard of what is to come, simply because they have less limitations put onto them.
This is certainly a great initiative taken by Valve and is sure to increase the appeal of the Left 4 Dead franchise even more now. In any event, you can count on the Left 4 Dead 2 mods becoming much more interesting.