Aside from the Geometrization Theorem/Poincare conjecture, probably the deepest theorem in low-dimensional topology in the last 10 years is the classification of hyperbolic structures on 3-manifolds with finitely generated fundamental group.  Aside from the topological type, it turns out they they are classified by certain invariants "at infinity" (either Riemann surfaces at infinity or so-called "ending laminations").  The proof of this uses work of an enormous number of people : Agol, Alhfors, Bers, Brock, Calegari, Canary, Namazi, Kleineidam, Kra, Lecuire, Marden, Maskit, Masur, Minsky, Mostow, Ohshika, Prasad, Rees, Souto, Sullivan, Thurston, and probably people I'm forgetting.