  We present further evidence for a dual conformal symmetry in the four-gluon
planar scattering amplitude in N=4 SYM. We show that all the momentum integrals
appearing in the perturbative on-shell calculations up to five loops are dual
to true conformal integrals, well defined off shell. Assuming that the complete
off-shell amplitude has this dual conformal symmetry and using the basic
properties of factorization of infrared divergences, we derive the special form
of the finite remainder previously found at weak coupling and recently
reproduced at strong coupling by AdS/CFT. We show that the same finite term
appears in a weak coupling calculation of a Wilson loop whose contour consists
of four light-like segments associated with the gluon momenta. We also
demonstrate that, due to the special form of the finite remainder, the
asymptotic Regge limit of the four-gluon amplitude coincides with the exact
expression evaluated for arbitrary values of the Mandelstam variables.
