General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degrees of freedom generated by the trace anomaly. At event horizons the conformal anomaly scalar degree(s) of freedom can have macroscopically large quantum back reaction effects on the geometry, potentially removing the classical event horizon of black hole and cosmological de Sitter spacetimes, replacing them with a boundary layer where the effective value of the gravitational vacuum energy density can change. In the effective theory, the cosmological term becomes a dynamical condensate, whose value depends upon boundary conditions near the horizon. By taking a positive value in the interior of a fully collapsed star, the effective cosmological term removes any singularity, replacing it with a smooth dark energy interior. The resulting gravitational condensate star (or gravastar) configuration resolves all black hole paradoxes, and provides a testable alternative to black holes as the final state of complete gravitational collapse. Scaled up to cosmological scales, the observed dark energy of our universe likewise may be a macroscopic finite size effect whose value depends not on microphysics but on the cosmological horizon.