Apple has released an update to iTunes 4, bringing it to version 4.0.1. According to Apple’s notes, iTunes 4…

(MacDailyNews Note: the release notes don’t say the 4.0.1 update increases AAC quality)

…features superior sound quality including support for MPEG-4 AAC audio. iTunes 4.0.1 includes a number of performance and network access enhancements, and only allows music sharing between computers using iTunes 4.0.1 or later on a local network (in the same subnet). If you have an Apple SuperDrive, you can archive your song files to a DVD disc as well as burn playlists to standard audio CDs to play in your car or home stereo.

No more sharing playlists and tunes over the Internet as Apple moves quickly to thwart nascent sharing schemes.

You can download the update through the Software Update Preference Pane or from Apple’s website here.