This afternoon Apple sent out 3 updates:
GarageBand v5.0.2 is 108 MB and has these release notes: “Improved purchasing experience for Artist Lessons in the GarageBand Lesson Store, and Accessing installed Jam Packs in the loop browser”.
QuickTime v7.6.2 is 60.3 MB and supports the new iTunes release. This update enforces a reboot.
iTunes v8.2 supports iPhones and iPod Touches running iPhone OS 3.0 (!!!!) and improves accessibility. By nature of requiring the new QuickTime this update will enforce a reboot.