  In analogy to the equidistribution of preimages of a prescribed point by the
iterates of a polynomial map in the complex plane towards the equilibrium
measure, we show here the equidistribution of points for which the derivative
of the n-th iterate of the polynomial takes a suitable prescribed value towards
the equilibrium measure. We then give a similar statement in the space of
degree d polynomials for the equidistribution of parameters for which the
n-derivative at a given critical value has a prescribed derivative towards the
activity current of the corresponding critical point.
