Monitor always on while streaming to apple tv

Hi,

I'm using home sharing from my mac pro to stream to the apple tv, and it works well. It wakes the mac when it's asleep, but the problem is that the monitor (30" acd) connected to the mac stays on as long as it's streaming to the apple tv.

I was hoping the new "low power wake" feature in lion would apply to streaming to apple tv, but that doesn't seem to be the case.

Any ideas how I can get the monitor to sleep as it should while streaming?