I have yet to see a game launch its SDK (or other mod tools) ontime. Now, knowing this, Tripwire probably should not have been quite so optimistic with their estimate, but I would be pretty surprised if it isn't here in a week or two, which is a lot better than the norm. In my experience, when a company claims they will have an sdk or tool ready on launch, they usually mean it will be ready 6 months later. And there are some companies (cough...creative assembly...cough) where any promise of extra tools "on release" actually means that they will post a message on the forums 1.5 years later that they aren't going to release the mod tools but the tools will be available on release in their next title. (which they won't)