For a finite subgroup G of SL_n(C), moduli spaces of G-constellations play an important role in the McKay correspondence since they are natural candidates of crepant resolutions of the quotient singularity C^n/G. In this talk I will explain how the birational geometry of these moduli spaces can be studied and show that every projective crepant resolution of C^3/G is indeed realized as such a moduli space.