  Wilson loops with lightlike polygonal contours have been conjectured to be
equivalent to MHV scattering amplitudes in N=4 super Yang-Mills. We compute
such Wilson loops for special polygonal contours at two loops in perturbation
theory. Specifically, we concentrate on the remainder function R, obtained by
subtracting the known ABDK/BDS ansatz from the Wilson loop. First, we consider
a particular two-dimensional eight-point kinematics studied at strong coupling
by Alday and Maldacena. We find numerical evidence that R is the same at weak
and at strong coupling, up to an overall, coupling-dependent constant. This
suggests a universality of the remainder function at strong and weak coupling
for generic null polygonal Wilson loops, and therefore for arbitrary MHV
amplitudes in N=4 super Yang-Mills. We analyse the consequences of this
statement. We further consider regular n-gons, and find that the remainder
function is linear in n at large n through numerical computations performed up
to n=30. This reproduces a general feature of the corresponding strong-coupling
result.
