Engadget has a great post on how to get music off of your iPod in both a Macintosh and Windows environment. Specifically, the post directs you to two different pieces of software that will help you retrieve music from your iPod depending on the OS you are running. I have used both pieces of software on my Mac and my PC, and both work equally well albeit with different interfaces. I do have to say that if you use a Mac and you have found iPodDownload to not be working after upgrading to iTunes 4.7, you should follow the tip outlined in my previous post to get iPodDownload functioning again as it is the most user-friendly Mac program that I have used.
There are other methods for retrieving your music from your iPod under both platforms; a simple Google search will provide you with many different methods, but the Engadget post and software recommendations are certainly a good place to get started.