Apple confirms very limited iPod nano flaw

Apple has officially confirmed an issue with some iPod nano screen, but this affect only a very small number of units :

This is a real but minor issue involving a vendor quality problem in a small number of units. Our figures show this issue has affected less than 1/10 of 1 per cent of the total iPod nano units that we've shipped. It is not a design issue.

In addition Apple has revealed that the iPod nano was manufactured using the same high-quality polycarbonate plastic as the fourth-generation iPod.
Complains about the iPod nano being easily scratched are probably affecting mostly the black model since it is easier to spot them.