ATI's decision to join up with AMD is already causing strange rumors to spread, including one involving Apple. With Apple's new reliance on Intel processors and their heavy usage of ATI GPUs, it leaves them in a sticky situation. As the article mention, Intel will not be renewing ATI's chipset license once it expires. Apple will have to make a decision as well, whether it be complete reliance on Intel's GMA graphics, switching to nVidia GPUs or even moving to a different platform. I think the article is correct in assuming that Apple will most likely give nVidia a try:

Will Intel allow Apple to continue to working with ATI on graphics after the company becomes wholly owned by rival AMD? I think that we'll probably see Intel gently "suggest" that Apple switch to another vendor for graphics technology in 2007. Once the dust settles I bet that all Macs from here on out will ship with graphics from either Intel or NVIDIA.
It will be interesting to see what the Mac-using community thinks about these possibilities, and what they would like to see happen.