I went back and looked at the CGTextures license in preparation for starting another thread to clarify this matter, and I saw the clause "It is NOT permitted to… Release the Textures or derivative products under Open Source Licences." So the issue is actually the CGTextures license, not CC. I'm going to start a new thread in General Discussion where we can get at this in more depth, since it's off-topic here. Look for "Creative Commons licensing questions."