  We demonstrate theoretically the possibility of using nano mechanical systems
as single photon routers. We show how EIT in cavity optomechanical systems can
be used to produce a switch for a probe field in a single photon Fock state
using very low pumping powers of few microwatt. We present estimates of vacuum
and thermal noise and show the optimal performance of the single photon switch
is deteriorated by only few percent even at temperatures of the order of 20 mK.
