Nike and Apple have teamed up to create a $29 iPod sport kit. With certain Nike shoes your iPod will be able to "talk" to your shoes and your iPod will be able to display certain workout statistics such as distance, time, speed, and calories. . This new iPod Sport Kit will only be available for certain Nike shoes named Nike+ Air Zoom Moire.
The Nike+iPod Sport Kit requires a Nike+ shoe and an iPod nano with a Mac® with a USB 2.0 ports and Mac OS® X version 10.3.9 or later and iTunes 6.0.5; or a Windows PC with a USB 2.0 port and Windows 2000, XP Home or Professional (SP2) and iTunes 6.0.5.
[update] Here is an ad for this new Nike product: