There are 2 types of Laptop Graphics...Integrated and Discrete. Both are usually integrated into the laptop's motherboard, which means that you can't remove it without killing your notebook. Integrated is usually something like the Intel GMA 900 or Extreme Graphics 2 etc. Discrete graphics is a video chip provided by a 3rd party, which usually would be nVIDIA or ATI, like the GeForce Go 6800 or the Mobility Radeon X800 etc.
nVIDIA is currently working on something called MXM, which stands for Mobile PCI-Express Modules.
It's basically a GPU core with the RAM on a small PCB with the PCI-E interface so you can swap when you upgrade. It's pretty innovative.