  We show how stationary entanglement between an optical cavity field mode and
a macroscopic vibrating mirror can be generated by means of radiation pressure.
We also show how the generated optomechanical entanglement can be quantified
and we suggest an experimental readout-scheme to fully characterize the
entangled state. Surprisingly, such optomechanical entanglement is shown to
persist for environment temperatures above 20K using state-of-the-art
experimental parameters.
