Gizmodo states that NVidia confirms the new chipset in MBP support up to 8 GB of RAM, Dual GPU capability, and on-the-fly switching. It can be put in place with a firmware/software/driver update. Here is hoping Apple incorporates this when available.
Article:
http://gizmodo.com/5067433/confirmed-apple-can-enable-dual-gpu-and-on+the+fly-switching-in-macbook-pro
Article:
http://gizmodo.com/5067433/confirmed-apple-can-enable-dual-gpu-and-on+the+fly-switching-in-macbook-pro