Life Fitness talks about plans to offer integration with Apple iPod players in upcoming exercise machines.

If you have been to a gym, you are familiar with the Life Fitness machines - they are almost everywhere.
Life Fitness works on new fitness machines with touch screens that let you navigate your iPod and playback audio and video content. At the same time the iPod enabled exercise machine will recharge the iPod battery.

The new iPod exercise machines from Life Fitness are supposed to start shipping in March. More details in this AP story on Yahoo!.
See also the Life Fitness site.