Apple Computer Inc. just posted an amazing article on how to identifying different iPod models. Apple provided a table describing each iPod release, Model Year-Month introduced, Scrolling device, Drive size and Current iPod Software Version. Apple also goes into “How to tell which model you have” and more.

Here is the introduction to the article;
This document will help you determine the model of iPod you have as well as the latest version of iPod software available for your model. To ensure that your Mac or PC is compatible, check the system requirements for your particular iPod.

You can always download the latest iPod software at http://www.apple.com/ipod/download/.

You can tell which iPod model you have by checking:

- If it has a scroll wheel, a touch wheel, or a Click Wheel.
- The size of its hard drive.
- If it has a color or monochrome screen.
- The dock connector.

http://docs.info.apple.com/article.html?artnum=61688