Good idea. I'd like to see something like this become more integral on Flickr. I've been doing some searching for ideas for album artwork, and I found something on Flickr I'd strongly consider using, but I'll still have to contact and negotiate and it would be nice to have a bit of a framework for doing so, so that the photographer isn't potentially put off or things the email isn't legit. This sounds a lot like what youlicense.com does for music, btw.