  It has been persuasively argued that the number of the effective degrees of
freedom of a macroscopic system is proportional to its area rather than to its
volume. This entails interesting consequences for cosmology. Here we present a
model based on this "holographic principle" that accounts for the present stage
of accelerated expansion of the Universe and significantly alleviates the
coincidence problem also for non-spatially flat cosmologies. Likewise, we
comment on a recently proposed late transition to a fresh decelerated phase.
