  We derive a compact all-loop-order expression for the IR-divergent part of
the N=4 SYM four-gluon amplitude, which includes both planar and all
subleading-color contributions, based on the assumption that the higher-loop
soft anomalous dimension matrices are proportional to the one-loop soft
anomalous dimension matrix, as has been recently conjectured.
  We also consider the Regge limit of the four-gluon amplitude, and we present
evidence that the leading logarithmic growth of the subleading-color amplitudes
is less severe than that of the planar amplitudes. We examine possible 1/N^2
corrections to the gluon Regge trajectory, previously obtained in the planar
limit from the BDS ansatz. The double-trace amplitudes have Regge behavior as
well, with a nonsense-choosing Regge trajectory and a Regge cut which first
emerges at three loops.
