Distance matrices, random metrics and Urysohn space
  We introduce an universum of the Polish (=complete separable metric) space - the convex cone of distance matrices and study its geometry. It happened that the generic Polish spaces in this sense of this universum is so called Urysohn spaces defined by P.S.Urysohn in 20-th, and generic metric triple (= metric space with probability borel measure) is also Urysohn space with non-degenerated measure. We prove that the complete invariant of the metric space with measure up to measure preserving isometries is so called matrix distribution - invarinat and ergodic measure with respect to infinite symmetric group which is concentrated on the cone of distance matrices. This defined an important new class of random matrices and family of random metrics on the naturals. 
A. Vershik (St.Petersburg Mathematical Institute of Russian Acad.,   Max-Planck-Institute, Bonn)