> Have you ever seen a project whose identity material is GPL?
To have the pictures or music of the identity (logos, theme songs) under GPL shouldn't be a problem...? The trademark is still there, so the logos (etc) is still protected. Copyright (or no) would just protect who can reprint/copy the material, it's still protected how you use the logo and you can't use it for any other project just because it's not under copyright.
