It worked in lion, you would activate a hot corner for display sleep, wait a few seconds, open lid and only the External would be active, MPB display off however i could still use the webcam and keyboard etc. In 10.8 I cant do this anymore. I want the gpu to power only the external. Any ideas? Thanks zz also i just tried this terminal hack, sudo nvram boot-args="iog=0x0" and it seems to work.