After Phoenix fell silent on November 2, the Jet Propulsion Laboratory announced that they'd carry on listening for faint transmissions from the spacecraft, using the two NASA orbiters, until the period of Mars conjunction began. Well, conjunction has begun, and JPL announced this morning that "The last attempt to listen for a signal from Phoenix was when [Mars] Odyssey passed overhead at 3:49 p.m. PST Saturday, Nov. 29 (4:26 p.m. local Mars solar time on the 182nd Martian day, or sol, since Phoenix landed)."
So that's really it for Phoenix. If, against all odds, it survives the Martian winter with solar panels intact and able to provide energy to an undamaged computer and telecommunications system, we won't hear from it again at least until October. I don't think that anyone at JPL really believes it'll make it, but they do have plans to listen again late next year, just in case that one-in-a-million possibility comes to pass.