Confirmed working on my system with no need to modify org.chameleon.Boot.plist.
EDIT: After one restart, my system froze up. Several times. So, I had to indeed add the line to my org.chameleon.Boot.plist. -- also, it appeared I had the problem when I switched from the "OS X Default Graphics Driver" to the "NVIDIA Web Driver" in the NVIDIA Driver Manager Preferences.
Even on the "OS X Default Graphics Driver" I get power management on my graphics card: EVGA GeForce GTX 670 4GB running on Asus Sabertooth x79 3930k