I would like to add that the Monoprice 4-1 HDMI switcher (product ID 5557) can do the same thing - that is, power on a standby display when the Apple TV or other HDMI input is activated.
http://www.monoprice.com/products/p...=10110&cs_id=1011002&p_id=5557&seq=1&format=2
Specifically, I plugged my AppleTV into this device and plugged the HDMI-out from this device into my 24" computer monitor in our living room (I lack a real TV, on a budget).
Using only the AppleTV remote to wake the device, it would then also automatically wake up my monitor in standby as well - I can only assume the standby wakeup signal is successfully carried by the Monoprice switcher. I do not know if the other Monoprice HDMI switchers act similarly.
It is also very handy that the Monoprice can break out stereo RCA L/R outputs from the AppleTV HDMI as well, since I lack optical stereo equipment.
This device worked very well for me. My only difficulty was that eventually (due to a surge, the product's limited lifespan, or my own mistake in wiring) the device stopped worked completely after about a year. Was very disappointed, as it was perfect.