Someone is using Haskell…
It looks like the guys at Linspire (formally Lindows) are using Haskell as their main language for OS development:
At Linspire, our choices have been OCaml and Haskell. David Fox wrote the hardware detector in OCaml and is now porting it to Haskell. Jeremy Shaw has been doing various utilities in Haskell for several years. Sean Meiners recently wrote an application for managing his recipe collection and is now hooked. I am porting our CD build procedure from OCaml to Haskell.
I wonder if this is the start of a renaissance period for functional languages. 
