Note that while both NVidia and Intel graphics are well supported in Ubuntu, Nvidia Optimus is a complelely different beast - it's a technology to seamlessly switch from an energy-efficient Intel chip to the powerful NVidia chip when an application requires some extra performance.

My understanding is that the current state of support of this feature in Linux is not complelely free of trickery. See Project Bumblebee for more details and be ready to get your hands dirty :)