SemiAccurate claims that Apple will be dropping NVIDIA-based designs in their next iMacs and laptops for at least the next few years. They claim the reason is due to the recent NVIDIA manufacturing defects which affected a number of MacBook Pros.
The shift back to Intel-based chipsets was not entirely unexpected, however, as Intel and NVIDIA have been under a licensing battle over whether or not NVIDIA can even produce Nehalem-based chipsets in the future. Apple currently uses the Nehalem processors for their Mac Pro line, and is expected to adopt the mobile Nehalem processors for its mobile line later this year.
The shift from Intel to NVIDIA chipsets, however, was responsible for notable gains in the low-end graphics processing power in the new MacBooks and iMacs which will also be leveraged in Apple's upcoming Snow Leopard operating system.