iTunes 3.0.1

is available for download via the OS X Software Update preference panel. From the Read Me file:

iTunes for Mac OS X lets you build and enjoy your personal digital music library on your Mac. This third generation of iTunes adds powerful new tools to help organize, personalize, and experience your music collection, including Smart Playlists, My Rating, Sound Check, and many other exciting features. iTunes 3 also supports Audible spoken word content so you can listen to best-seller audio books and premium publications on your Mac and iPod.

We installed it on all of the above Macs with no problem.