Haskell introduces a whole range of features such as type classes, lazy evaluation, and monads for imperative programming. Judging from the number of libraries available for Haskell (especially the Glasgow Haskell Compiler GHC), we can go a long way with this unique programming model. It remains to be seen if these concepts will be adopted by mainstream programming languages (or if Haskell becomes one of them). As a first indication we saw that Python definitily benefits a lot from the adoption of Haskell's list comprehensions.
Haskell's treatment of operators combines the "normal" infix notation and strong typing with the advantages of Scheme when passing operators as (function) values to other functions.