Previously Nvidia's switching did allow both cards to be on.
By the way, I just read in an older article on arstechnica that Apple uses its own implementation of automatic graphics switching, not Optimus. This custom implementation seems to always power down the iGPU/dGPU if the other GPU is active. Optimus, AFAIK, only powers down the dGPU.
http://arstechnica.com/apple/2010/04/inside-apples-automatic-gpu-switching/
It would be nice if Apple would provide an optional manual control over the active GPU as well as the option to have both enabled at the same time. Although gfxCardStatus seems to work nicely, I would prefer a native solution.
----------
True but what if you're using bootcamp to run a CAD application?.. Then u are stuck with the weaker (in the case of CAD) gt750 card....gfxcardstatus is only a mac OSX app!
You can use Nvidia's drivers under Windows. They provide the same functionality. Here is an official demo from Nvidia: http://www.youtube.com/watch?v=Zh4HCadTY_A