It's official now.

Photoshop CS3 extended can open COLLADA models, use the 3D model in a layer, apply usual Photoshop tools on this layer, in addition to rotating/translating or slicing the 3D model.

But even more interesting for game developers, you can now click on any of the texture, edit it, and see the 3D model updated with the new texture. This will be a huge gain of productivity, no need to save the textures, reload in Max/Maya/Softimage....