Nvidia lost their Apple contract for the current generation of Apple hardware for whatever that was worth.
The previous C2D based MBPs, MBs, iMacs, etc. all used Nvidia chipsets to include both integrated Nvidia video as well as discrete GPUs. All of the Sandy Bridge based Macs are currently using AMD discrete GPUs. Apple does tend to flip flop between GPU vendors though.
While Nvidia support is still arguably better for consumer cards (gaming) as well as professional workstation cards, it doesn't seem as though the differences are such that they warrant choosing Nvidia over AMD. Possibly unless you're buying a workstation card.







