According to the French 3D-decitated website Generation 3d, AMD/ATI could be on track to release high-end graphic cards based on multi-core GPU by the end of the year. If one can already use several graphic cards in the same computer via nVidia SLI or ATI CrossFire, multi-core-based GPU will offer several advantages to today dual GPU graphic cards, as it will be easier to manufacture and performance wise more efficient.
However, ATI/AMD will have to work hard to deliver optimized drivers, and as Windows version will most likely the first one to be released, one can imagine that Apple drivers will not be for the date of availability of such cards. It will imply for Cupertino to allocate resources for optimizing such drivers, and why not implementing multithreading for OpenGL management for both CPU and GPU.
[translation by Linathael