  We describe thermal melting of the two-dimensional vortex lattice in a
rotating superfluid by generalizing the Halperin and Nelson theory of
dislocation-mediated melting. and derive a melting temperature proportional to
the renormalized shear modulus of the vortex lattice. The rigid-body rotation
of the superfluid attenuates the effects of lattice compression on the energy
of dislocations and hence the melting temperature, while not affecting the
shearing. Finally, we discuss dislocations and thermal melting in inhomogeneous
rapidly rotating Bose-Einstein condensates; we delineate a phase diagram in the
temperature -- rotation rate plane, and infer that the thermal melting
temperature should lie below the Bose-Einstein transition temperature.
