iTunes 7 has a new feature that will transfer purchased music from an iPod to the iTunes library of any computer authorized to play its music (you can authorize up to five computers to play music purchased with a given account):
1. Sync your iPod with the computer that pruchased the music.
2. Connect that iPod to another authorized computer, and you are given two options:
a. "Erase and sync" the iPod with 2nd computer, severing the link to the 1st computer.
b. Execute a one way "Transfer purchased music" from the iPod to the 2nd, authorized computer's iTunes Library.
These two items also available in the File menu.
[kirkmc adds: At first glance, I wasn't going to run this hint, since it is a feature that Apple has mentioned in its iPod feature list. However, seeing that it is poorly documented in the iTunes help (much of the iTunes help looks like it wasn't updated to cover this feature, and finding an explanation is not easy), I figured it was worth pointing out. It's a great way to purchase music from one computer then transfer it to other computers in your household, for example, rather than using a network or using the iPod in disk mode.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20061016211125125