  We show that a two-dimensional (2D) array of 1D interacting boson tubes has a
deconfinement transition between a 1D Mott insulator and a 3D superfluid for
commensurate fillings and a dimensional crossover for the incommensurate case.
We determine the phase diagram and excitations of this system and discuss the
consequences for Bose condensates loaded in 2D optical lattices.
