The most recent distance measurements of Type Ia supernovae strongly
favour an acceleration of the expansion of the Universe, implying the
existence of a repulsive, non-self-gravitating vacuum energy density.
We look at these results as well as the remarkable concordance of
results from studies of the cosmic microwave background, gravitational
lensing, and other cosmological data, making a significant
observational case for a non-zero value for Einstein's cosmological
constant 
.
