Apple has released iTunes 10.5 via software update, the first release in a series leading up to the expected public release of iOS 5 on Wednesday.
iTunes 10.5 introduces iCloud to the software along with automatic downloads. You can also download previous music, TV, app and book purchases again at no additional cost. Some previous purchases might not be available because they are no longer available through iTunes.
It also adds Wi-Fi syncing, which automatically syncs an iPhone, iPad or iPod touch with iTunes any time they're both on the same Wi-Fi network, one of the key features of iOS 5.
iTunes 10.5 is required to sync an iPhone, iPad or iPod touch with iOS 5.
iTunes 10.5 is a 60.9 MB download and is available through with Software Update or a direct download from Apple.
Update: iTunes 10.5 is now available from Apple's site.