This site gives details on how to record audio using your iPod without any addons…well, at least addons that cost money.

First thing you have to do is install PodZilla, which is essentially a port of the linux kernel for the iPod. Once you have that installed, you can boot into linux and use the headphone jack to record using a microphone or even your headphones. It apparently allows you to chose up to a 96khz sample rate, which is pretty good quality.

I wonder how long it will be before concert tapers are using their iPods instead of DAT recorders. I know of a few that use laptops, and have seen some that use Nomads.