  We discuss a cosmology in which cold dark matter begins to decay into
relativistic particles at a recent epoch (z < 1). We show that the large
entropy production and associated bulk viscosity from such decays leads to an
accelerating cosmology as required by observations. We investigate the effects
of decaying cold dark matter in a Lambda = 0, flat, initially matter dominated
cosmology. We show that this model satisfies the cosmological constraint from
the redshift-distance relation for type Ia supernovae. The age in such models
is also consistent with the constraints from the oldest stars and globular
clusters. Possible candidates for this late decaying dark matter are suggested
along with additional observational tests of this cosmological paradigm.
