http://leventerkok.github.com/sbv/

SBV (SMT Based Verification) is a library that allows Haskell programs to take advantage of modern SMT solvers, by providing a symbolic simulation engine that can invoke 3rd party SMT solvers to prove/falsify properties about (a certain class of) Haskell programs.

New in this release is the support for the CVC4 SMT solver: http://cvc4.cs.nyu.edu/web/

If you were planning to use SMT solvers before, but were worried about the not-so-commercial-friendly licenses of Yices and Z3, then this is a great opportunity: CVC4 comes with essentially no limit on its use for research or commercial purposes!