Nvidia Optimus GPU Switching For Linux has been released.
Nvidia Optimus is a technology available for notebooks, used to increases battery life by switching the dedicated GPU off when it’s not needed and then switching it on again when it’s needed. When the dedicated GPU is off, the integrated graphics chip is used.
Nvidia Optimus GPU switching is officially only supported on Windows 7, but it’s also unofficially available on Linux thanks to the Bumblebee project.