my 3G doesn't list it externally, but you should be able to find it by: Settings-->About
i'm pretty sure what you are looking for is "model".. in the case of my original 15GB 3G (the one that came with a dock) it is M9460LL
if it is 4G, you should be able to find it on the apple.com/ipod page.. under "tech specs" somewhere...
good luck and enjoy your 'pod
reality
edit: for current ipods (4G and mini):
M9160LL/A (silver)
M9437LL/A (gold)
M9436LL/A (blue)
M9435LL/A (pink)
M9434LL/A (green)
M9282LL/A (20GB)
M9268LL/A (40GB)