A couple of hackers have spent some time converting the new graphical user interface that came with iPod nano third generation and the iPod classic, to work even with older iPod 5G and 5.5G. The only thing that doesn’t currently work is the cover flow functionality. You better know what you’re doing if you are about to install this unofficial firmware hack since some users have bricked their iPods while installing this.

5G iPods hacked to run updated interface [Engadget]