  We consider the effect of rapid rotation on the light curves of neutron stars
with hot polar caps. For $P \approx 3$ms spin periods, the pulse fractions can
be as much as an order of magnitude larger than with simple slowly-rotating
(Schwarzschild) estimates. Doppler boosting, in particular, leads to
characteristic distortion and ``soft lags'' in the pulse profiles, which are
easily measurable in light curves with moderate energy resolution. With $\sim
10^5$ photons it should also be possible to isolate the more subtle distortions
of light travel time variations and frame dragging. Detailed analysis of high
quality millisecond pulsar data from upcoming X-ray missions must include these
effects.
