G4 TV has brought to fruition an interview with Gabe Newell of VALVe Software regarding Left 4 Dead 2. In this interview it has been confirmed that VALVe still aren't quite ready to unbound Episode 3 details upon the community at large, as yet. Here's an excerpt:

G4: So, you don't regret it??

Newell: I want to make sure that I don't sound like I'm dismissing user's issues, right? I get a ton of email everyday saying why aren't you talking about Episode 3? And there are very good reasons why we're not talking about Episode 3, which I can't talk about yet, but I will. So, I think there's frustration there and I'm not somehow going to say that that's not legitimate or length isn't a concern or regularity. The speed with which these updates are coming out, people say,Hey, gee, these episodes are supposed to be shorter and you take 25 years to ship each one. So, I don't wanna somehow dismiss those, or sort of throw them under - but I think we're in much better shape than would have been, in terms of our ability to move stuff, technology, products, uh, forward faster by changing how, ya know, being different than, ya know, there was Half-Life 2, and then there was post-Half-Life 2 in terms of how we were approaching these things and yea, I think that we're overall pretty happy without somehow dismissing the legitimate complaints that people should have towards us. But, we're happy with that choice that we made.