  Positive evidence for neutrino oscillations is mounting from the solar and
atmospheric neutrino anomalies and the LSND experiment. Accordingly, the
neutrino mass differences appear to lie in the sub-eV range and at least some
of the mixing angles appear to be large. We explore some of the consequences of
this picture for supernova (SN) physics and cosmology. In particuler, we
discuss if a conflict between the solar vacuum solution and the SN 1987A signal
can be avoided, and the role of future cosmic microwave background measurements
to reveal the presence of a cosmological hot dark matter component.
