The new iPod Nanos were unveiled earlier this month at a special event which see all but the Shuffle get updated even if it was only a capacity change.
But something that Steve Jobs didn't mention seems to have occurred 4GB Nanos, these unannounced Nanos are shipping across Europe and Canada and are retailing for between €119 and €130 each.
It would appear that Apple was manufacturing 4GB and 8GB Nanos before their launch and then decided to scrap the 4GB and make a higher capacity 16GB model leaving the 8GB as the entry Nano.