Due to a potential for exploding batteries, Apple recently instituted a recall on all 1G iPod Nanos, of which I had two (one with 2GB capacity and one with 4GB). I sent them off and, after a pretty long turnaround time (nearly two months altogether), I've received my first replacement: a brand new 6th generation touchscreen iPod Nano with 8GB capacity :D
If you happen to have one or more of the old models, I recommend you take advantage.