The new 4th-gen iPod nano was introduced during Apple's Let's Rock event on 09/09/2008. It was introduced by Steve Jobs in 8GB and 16GB guises. Unofficially though, I read through Macrumors that a limited amount of 4th-gen 4GB iPod nanos were released too. I'm lucky cause I spotted a 4th-gen 4GB iPod nano while I was shopping in Tesco the other day. The salesperson let me take some photos of it so, thanks! It's the one in the green colour.
Yep, the 4th-gen iPod nano it is.
It is a certified original Apple product.
Sent from my MacBook Pro.