  The dispersion in the peak luminosities of high redshift type Ia supernovae
will change with redshift due to gravitational lensing. This lensing is
investigated with an emphasis on the prospects of measuring it and separating
it from other possible sources of redshift dependent dispersion. Measuring the
lensing induced dispersion would directly constrain the power spectrum of
density fluctuations on smaller length scales than are easily probed in any
other way. The skew of the magnification distribution is related to the
bispectrum of density fluctuations. Using cold dark matter models it is found
that the amount and quality of data needed is attainable in a few years. A
parameterization of the signal as a power law of the angular size distance to
the supernovae is motivated by these models. This information can be used in
detecting lensing, detecting other systematic changes in supernovae and
calculating the uncertainties in cosmological parameter estimates.
