  Measured time delays between the images of a gravitationally lensed source
can lead to a determination of the Hubble constant ($H_o$), but only if the
lensing mass distribution is well understood. The inability to sufficiently
constrain galaxy mass models results in large uncertainties on the derived
$H_o$, and severely hampers the cosmological application of this otherwise
elegant method. At the same time, lensing must compete with new techniques that
have the potential to measure the Hubble constant to within a few percent by
the middle of the decade. In this letter we re-evaluate the role of strong
gravitational lensing in the age of precision cosmology, and present a series
of Monte Carlo simulations that demonstrate the effect of the galaxy mass
distribution on Hubble constant determination. Though most gravitational lens
systems are unlikely to contribute significantly to precision studies of the
cosmological distance scale, the strong dependence of predicted time delays on
the galaxy mass profile suggests that the most useful and interesting results
may be obtained by running the traditional lensing problem in reverse --
namely, combining measured time delays with a well-constrained value of $H_o$
to study galaxy mass distributions.
