Finally, Nvidia has unveiled the Optimus Graphics technology for the mobile platform. As reported earlier, the Optimus technology automatically chooses and switches the best fit graphics chip between integrated graphics and discrete graphics. Besides that, this technology also switches back to the graphics which will help conserve battery life.
Nvidia cites the example of Hybrid car that chooses best system between electric car engine and gas-powered system on-the-fly, Optimus does the same for graphics processors on notebooks. Optimus technology for notebooks is seamless, instantaneous and most importantly - automatic. Users won't have to fiddle around any settings or buttons. Basically, this technology makes an automatic choice of using either discrete graphics or integrated graphics for running a program and also ensures better performance along with longer battery life.
Nvidia claims that battery charge on Optimus equipped notebooks can last up to two times longer than the notebooks without Optimus technology and discrete GPU.

As it is obvious, Nvidia's Optimus technology would be available only to the Nvidia GPU bearing notebooks. Asus would be the first one to roll out Optimus equipped notebooks - Asus UL50Vf, N61Jv, N71Jv, N82Jv, and U30Jc models.
Check out Nvidia's Optimus technology overview video:

NVIDIA Optimus Technology - The Best Notebook Experience from Techspot on Vimeo.