  A characteristic feature of small-x lepton-proton data from HERA is geometric
scaling -- the fact that over a wide range of x and Q^2 all data can be
described by a single variable $Q^2/Q_{sat}^2(x)$, with all x-dependence
encoded in the so-called saturation momentum $Q_{sat}(x)$. Here, we observe
that the same scaling ansatz accounts for nuclear photoabsorption cross
sections and favors the nuclear dependence $Q_{sat,A}^2\propto
A^{\alpha}Q_{sat}^2$, $\alpha \simeq 4/9$. We then make the empirical finding
that the same A-dependence accounts for the centrality evolution of the
multiplicities measured in Au+Au collisions at RHIC. It also allows to
parametrize the high-p_t particle suppression in d+Au collisions at forward
rapidities. If these geometric scaling properties have a common dynamical
origin, then this A-dependence of $Q_{sat,A}^2$ should emerge as a consequence
of the underlying dynamical model.
