NVIDIA today introduced "MXM" (which stands for Mobile PCI Express Module) a non-proprietary interface based on PCI-Express that has the purpose of giving notebooks an universal GPU socket platform, making upgradable laptop graphics possible, much like you do with desktop CPUs nowadays.

This same idea has been revisited a few times, I can even recall the old Rendition trying to put up something similar based on the AGP bus. Apparently though, with PCI Express and fewer graphics chip manufacturers out there the transition to a standarized open platform is more viable. NVIDIA seems to have some industry support already, though the big question remains, whether ATI will come up with its own platform or will agree to adopt NVIDIA's. Hardocp and HotHW have write ups on the announcement as well.