For arbitrary gauge groups, I will describe how one can check at the one-instanton level that the Nekrasov partition function of pure N=2 super Yang-Mills is equal to the norm of a certain coherent state of the corresponding W-algebra. For non-simply-laced gauge groups, this coherent state is in the twisted sector of a simply-laced W-algebra. I will also talk about the case of gauge theories with hypermultiplets.