In one of the demo videos on the site, it shows that Aperture can export a picture you're working on to an "external editor", make changes, and put it right back into the stack for that image. The other editor looked like Photoshop, but they cropped out the menu bar at the top you can't tell. Just looking at it though... This makes it seem that Apple is setting this app up right alongside Photoshop. You keep track of all your thousands of images in Aperture and do minor image editing inside. All the really powerful image manipulation they leave to Photoshop. Smart plan if you ask me.