Apple has released version 4.6 of its iTunes audio software via Software Update and Web download. According to the (brief) release notes:
"iTunes 4.6 includes support for playing your music wirelessly using AirPort Express with AirTunes. It also includes a number of other minor enhancements."
UPDATE We previously covered (1, 2) an issue where iTunes 4.5 would not share Libraries containing more than 28,899 tracks. We've received reports from several MacFixIt readers that iTunes 4.6 fixes this problem. Reader "Gryffin" writes:
"I just upgraded to iTunes 4.6 on both my server (PowerMac G4 667) and my "living room" computer (Toshiba Portégé 7200), and I'm happy to report that the Toshiba read all 21,543 songs from the server with no problem. In fact, while I didn't time it, it seemed to load them faster than it used to under iTunes 4.1."
An Apple Knowledge Base article about this issue has been updated to confirm this fix: "Update to iTunes 4.6 to prevent this from occuring."