Both [the 2GB and the 4GB iPod nano] devices feature the wonderfully simple color menu system that the high-end iPod uses. However, the iPod nano also includes some extras you won't find anywhere else, including a multiple-time-zone clock, a stopwatch (perfect for you music-loving athletes), and a few new games. Apple has also added the ability to synchronize Microsoft Outlook contacts and calendars, making the iPod nano a handy PIM replacement, as well. Battery life is exceptional... Sound quality is superb, thanks to enhanced audio circuitry that first debuted in the iPod shuffle.  -   Paul Thurrott     Quotes
Both [the 2GB and the 4GB iPod nano] devices feature the wonderfully simple color menu system that the high-end iPod uses. However, the iPod nano also includes some extras you won't find anywhere else, including a multiple-time-zone clock, a stopwatch (perfect for you music-loving athletes), and a few new games. Apple has also added the ability to synchronize Microsoft Outlook contacts and calendars, making the iPod nano a handy PIM replacement, as well. Battery life is exceptional... Sound quality is superb, thanks to enhanced audio circuitry that first debuted in the iPod shuffle. Paul Thurrott
 Color