With the release of updated iPod nano models today bearing new features such as large icons, enhanced fitness features, and sixteen new clock faces.
From Apple's press release announcing the new iPod nano:
iPod nano now features larger icons for even easier navigation of its intuitive Multi-Touch user interface, and you can choose from 16 new digital clock faces, ranging from classic analog looks to your favorite Disney characters including Mickey Mouse and Minnie Mouse. iPod nano now tracks your runs and walks right out of the box with no accessory required, making it even easier to get your fitness program up and running. iPod nano can track the time, pace and distance of your run, the calories you burn, and the number of steps you walk. iPod nano encourages you with motivational real-time voice feedback during your run, available in seven languages, while listening to your favorite music or FM radio station. You can also easily upload workouts to the Nike+ website to set goals, track your progress and challenge friends.
In addition to the new iPod nano models introduced today, Apple has made the software update available to the previous-generation models released in September 2010. Those iPod nanos carry the same form factor as the current models, and will be essentially identical to the current iPod nanos once the software update has been applied.