Yeah, Brasso works well - I've used it myself. It will completely remove scratches from the chrome on the back and leave it looking scratch free. It takes a lot of rubbing though for deeper scratches. On my iPod, I had some fairly deep scratches and I used a towel and spent about 25 minutes rubbing Brasso in - I could see gradual progress and when I was done it looked perfect.
Don't use it on the front though - it will remove scratches from the front as well, but leaves behind a faint haze to the screen, the front ends up looking like it has a matte finish or something - on mine the front looked better before I tried using Brasso on it.