HotHardware.Com posted a preview on NVIDIA Optimus Mobile Technology

Ideally, switchable graphics would be seamless. Launch an application that doesn't require significant graphics resources, and chipset graphics gets used. Fire up a game and the discrete GPU kicks in. Up to this point, a scenario like this simply wasn't available without a hard switch over and possible reboot but NVIDIA aims to change that with the release of their Optimus technology.

NVIDIA Optimus Mobile Technology Preview