  We review how (dimensionally regulated) scattering amplitudes in N=4
super-Yang-Mills theory provide a useful testing ground for perturbative QCD
calculations relevant to collider physics, as well as another avenue for
investigating the AdS/CFT correspondence. We describe the iterative relation
for two-loop scattering amplitudes in N=4 super-Yang-Mills theory found in C.
Anastasiou et al., Phys. Rev. Lett. 91:251602 (2003), and discuss recent
progress toward extending it to three loops.
