  Let S be a non-exceptional oriented surface of finite type. We discuss the
action of subgroups of the mapping class group of S on the CAT(0)-boundary of
the completion of Teichmueller space with respect to the Weil-Petersson metric.
We show that the set of invariant Borel probability measures for the
Weil-Petersson flow on moduli space which are supported on closed orbits is
dense in the space of invariant Borel probability measures.
