As NewMexiKen already noted, the new iTunes 7 is a major upgrade. If you have an iPod or use iTunes to manage your music, don’t hesitate to upload the new version.
Seen above is one of two new browsing interfaces. This is Cover Flow. With it, you can browse your music as if you were thumbing through albums — and if you don’t have the art, iTunes will get it for you.
Much better interface for managing iPods, too.
Update: How To: Back up your music using iTunes 7 from The Unofficial Apple Weblog (TUAW).