Apple is one of the most popular brands in computers inside the U.S. and has been using NVIDIA GPUs in many of its products like its line of MacBooks for a while. The NVIDIA 9400 series GPUs that Apple was using were subject to significantly higher than normal failure rates leading to many notebooks failing or having issues with graphics. After such failures, many wouldn't be surprised if Apple is seeking a new GPU supplier for its computers.
AMD has announced that its line of Radeon HD 4000 series discrete graphics cards will now be featured inside Apple iMac and Mac Pro desktop computers. AMD's video cards fully support the OpenCL version 1.0 implementation used in Apple's just released Snow Leopard operating system.
OpenCL allows developers to write software that is evenly distributed across the CPU and GPU. ATI says that its HD 4870 video card will be offered inside the Mac Pro computer and that its HD 4850 will be offered inside iMac systems.