  I discuss the relation of Hochschild cohomology to the physical states in the
closed topological string. This allows a notion of deformation intrinsic to the
derived category. I use this to identify deformations of a quiver gauge theory
associated to a D-branes at a singularity with generalized deformations of the
geometry of the resolution of the singularity. An explicit map is given from
noncommutative deformations (ie, B-fields) to terms in the superpotential.
