The scratches on the back of my white 3GS was really starting to annoy me so I ordered Rad Tech's Ice Creme to get it out. But even after repetitive application and wiping with the soft cloth, it really wasn't doing much for the deep scratches on the back. So I took the rougher sand paper that came with the kit (that was meant for polishing metal) and started scrubbing the plastic. The white plastic started coming off easily and after a slow process, I managed to get all the scratches out. The side effect was that the area around the scratches where I had scrubbed was now pure matte. I tried polishing it with the polishing cream but that didn't help. So with a stroke of genius, I decided to just sand the whole back so it'd be an even matte. Check out the results. Remember the black "matte iPhone" that was leaked before the 3GS came out? I think I've now got the white version.