SLI Hybrid in MacBook Pro: Not So Integrated in Mac OS X Yet

One of the main new features in the MacBook Pro is the NVidia SLI Hybrid technology based on the integrated chipset GeForce 9400M associated to the discrete GeForce 9600M GTS. This function is theoretically a great feature for saving battery life time when the user does not need 3D rendering. On Apple website, there is a dedicated webpage announcing a gain of 1 hour battery life time when using only the integrated graphical chipset instead of the discrete GPU.
However, it is not as magic as one could have understand it from yesterday's keynote according to a TechNote released by Apple. Indeed, to switch from the integrated video more to power mode is not transparent and not managed automatically by the system yet. One will have to select an option in the power saving panel in system preferences... that's NOT all. You will need to log out from your session, then log in again to have the new video mode activated.
For sure, this procedure will most likely evolve and disappear with Mac OS X Snow Leopard, and one can expect that the switch will be summarized to a simple selection in a dropping menu on the Apple tools bar. With Son Leopard, Open CL will be able to manage several GPU simultaneously, so one can even imagine that the system will directly control which integrated or discrete processor is activated or not.