Integrable hierarchies in Donaldson-Witten and Seiberg-Witten theories

We review various aspects of integrable hierarchies appearing in N=2 supersymmetric gauge theories. In particular, we show that the blowup function in Donaldson-Witten theory, up to a redefinition of the fast times, is a tau function for a g-gap solution of the KdV hierarchy. In the case of four-manifolds of simple type, instead, the blowup function becomes a tau function corresponding to a multisoliton solution. We obtain a new expression for the contact terms that links these results to the Whitham hierarchy formulation of Seiberg-Witten theories.