  Motivated by a recent experiment, the distribution of electric dipole
strength in the neutron-rich 68Ni isotope was computed using a relativistic
random phase approximation with a set of effective interactions that - although
well calibrated - predict significantly different values for the neutron-skin
thickness in 208Pb. The emergence of low-energy "Pygmy" strength that exhausts
about 5-8% of the energy weighted sum rule (EWSR) is clearly identified. In
addition to the EWSR, special emphasis is placed on the dipole polarizability.
In particular, our results suggest a strong correlation between the dipole
polarizability of 68Ni and the neutron-skin thickness of 208Pb. Yet we find a
correlation just as strong and an even larger sensitivity between the
neutron-skin thickness of 208Pb and the fraction of the dipole polarizability
exhausted by the Pygmy resonance. These findings suggest that the dipole
polarizability may be used as a proxy for the neutron skin.
