Oh, I think it is perfectly possible to do webprogramming in Haskell. In fact, Haskell would be my first choice if doing web development. In my opinion the reason there is not much focus on web programming in Haskell is that (based on my observations in #haskell) the average Haskell programmer would rather work on these "hard" problems then on web programming.
Not to get into the whole Blub language argument, but I daresay the average Haskell programmer is more advanced then your average web programmer. This is not to imply the latter is somehow easier or trivial (working IE support? I'm not ever gonna call that easy....) but it could explain a different focus of the community. Resulting in less webprogramming being done. That said, I've seen 5i7 Haskell webprogramming frameworks pop up in the past 2 years, so I'm not the only one who thinks it is perfectly suited for that.
I wouldn't say average haskell programmers just want to tackle hard problems, I'd say it's more that average Haskellers are experts or have interests in very specific fields that don't tie in with the 'mainstream' programming mindset.
