The process of black holes colliding and merging has been studied a
good deal, mostly by computer models based on General Relativity. You
could say that a black hole is already a sort of tear in the space-time
fabric, but if I understand correctly, no really new effects come out
of the collision of black holes. However, the resulting gravitational
radiation might be measurable, which would be pretty exciting.
Mike W.
(published on 10/22/2007)