Apple late yesterday released iTunes 5.0.1 which features several stability improvements. iTunes 5 features a new even more powerful instant search, including the new Search Bar which helps you find exactly what you are looking for in iTunes or from among 2 million songs on the Music Store, folders for organizing playlists, and new Parental Controls for music, music sharing and podcasts.
iTunes 5.0.1 is available via Mac OS X Software Update and also as a standalone installer (13.8MB). More info and download link here.