  The radiation pressure of two detuned laser beams can create a stable trap
for a suspended cavity mirror; here it is shown that such a configuration
entangles the output light fields via interaction with the mirror.
Intra-cavity, the opto-mechanical system can become entangled also. The degree
of entanglement is quantified spectrally using the logarithmic negativity.
Entanglement survives in the experimentally accessible regime of gram-scale
masses subject to thermal noise at room temperature.
