Doing a little searching, it seems it might be tied to the hardware as well, not just the OSX version (not sure if that's a real hardware limitation or a driver

Doing a little searching, it seems it might be tied to the hardware as well, not just the OSX version (not sure if that's a real hardware limitation or a driver issue though). The dual-GPU MacBook Pros from mid-2010 onwards have "automatic graphics switching" that does it on the fly: http://support.apple.com/kb/HT4110 http://support.apple.com/kb/HT4110 You're right that the 2008/09 models required logging out/in to switch manually; I hadn't realized that: http://support.apple.com/kb/HT3207 http://support.apple.com/kb/HT3207