  We study numerically conductance fluctuations near the integer quantum Hall
effect plateau transition. The system is presumed to be in a mesoscopic regime,
with phase coherence length comparable to the system size. We focus on a
two-terminal conductance G for square samples, considering both periodic and
open boundary conditions transverse to the current. At the plateau transition,
G is broadly distributed, with a distribution function close to uniform on the
interval between zero and one in units of e^2/h. Our results are consistent
with a recent experiment by Cobden and Kogan on a mesoscopic quantum Hall
effect sample.
