The next version of Adobe Photoshop is supporting hardware acceleration.

TG Daily reports about a Photoshop presentation with GPU support that sounds very promising. Quote:" 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."
The CS Next Suite (CS4) is scheduled for an October release. More details on TG Daily.