http://www.macrumors.com/2008/05/24/next-version-of-photoshop-to-be-gpu-accelerated/
So, what can you do with general-purpose GPU (GPGPU) acceleration in Photoshop? We saw the presenter playing with a 2 GB, 442 megapixel image like it was a 5 megapixel image on an 8-core Skulltrail system. Changes made through image zoom and through a new rotate canvas tool were applied almost instantly. Another impressive feature was the import of a 3D model into Photoshop, adding text and paint on a 3D surface and having that surface directly rendered with the 3D models' reflection map.