How do I determine which graphics card is being used?

[Scott Beamer]

My brand spanking new laptop[1] comes with nVidia "optimus"[2] technology.

[1]http://j.mp/cWjiSd
[2]http://www.nvidia.com/object/optimus_technology.html

I wasn't expecting Linux support (yet)  But I was expecting Ubuntu to 
recognize my nVidia GeForce GT 325M card.

It shows up ($ lspci) but how do I tell if Ubuntu is using it, or the 
onboard Intel graphics?

Also this laptop runs hotter under Ubuntu than it does under Windows 7 
(maybe that's my clue that Ubuntu is indeed using the nVidia card?).

Thanks.

Scott