  We present revised and improved mid-infrared Period-Luminosity (PL) relations
for Large Magellanic Cloud (LMC) Cepheids based on double-epoch data of 70
Cepheids observed by Spitzer at 3.6, 4.5, 5.8 and 8.0um. The observed scatter
at all wavelengths is found to decrease from +/-0.17 mag to +/-0.14 mag, which
is fully consistent with the prediction that the total scatter is made up of
roughly equal contributions from random sampling of the light curve and
nearly-uniform samplings of stars across the instability strip. It is
calculated that the Cepheids in this sample have a full amplitude of about 0.4
mag and that their fully-sampled, time-averaged magnitudes should eventually
reveal mid-infrared PL relations that each have intrinsic scatter at most at
the +/-0.12 mag level, and as low as +/-0.08 mag after correcting for the tilt
of the LMC.
