Apple on Wednesday released iTunes 9.2, an update to its media and syncing software for the iPhone, iPod touch, and iPad.

iTunes 9.2 adds a handful of features, chiefly compatibility with iOS 4 and iPhone 4, both of which are slated for release next week. In addition, the update introduces book syncing and reading with an iPhone or iPod touch running iBooks 1.1, and support for organising and syncing PDF documents as books.

iTunes 9.2 also supports the new Folders feature in iOS 4 that lets users organise apps into groups (if you synced a device running a build of iOS 4 with a previous iTunes version, your folders would be blown away and all apps would wind up spread out across home screen pages). The updated version should allow for much faster backups while syncing an iPhone or iPod touch running iOS 4 (but, notably, not previous iOS versions), and album artwork should appear more quickly when exploring your library.

iTunes 9.2 is available now via Software Update and at Appleā€™s site for both Macs and PCs.