TG Daily is reporting that Adobe recently previewed the next version of Photoshop (CS Next / CS4) with GPU acceleration. And as expected it made for an enormous improvement in speed. They they observed "the presenter playing with a 2 GB, 442 megapixel image like it was a 5 megapixel image on an 8-core [Intel] Skulltrail system."
There was no specific mention of the Mac version (the demo seems to have been done on a Windows machine) and also no discussion of if and how the 32-bit limitation of CS4 on the Mac might affect this GPU assisted performance boost. Nonetheless, the addition of GPU acceleration is a big deal, and perhaps will push Apple into getting more high performance graphics cards into its systems.