iTunes in the Cloud. iTunes now stores your music and TV purchases in iCloud and makes them available on your devices anywhere, any time, at no additional cost.
Automatic Downloads. Purchase music from any device or computer and automatically download a copy to your Mac and iOS devices.
Download Previous Purchases. Download your past music, TV, app, and book purchases again, at no additional cost. Previous purchases may be unavailable if they are no longer on the iTunes Store.
Sync with your iPhone, iPad, or iPod touch with iOS 5.
Wi-Fi Syncing. Automatically sync your iPhone, iPad, or iPod touch with iTunes any time they're both on the same Wi-Fi network.
For information on the security content of this update, please visit: http://support.apple.com/kb/HT1222.
If you're going to be updating to iOS 5 tomorrow, update to iTunes 10.5 today. (Jailbreakers, we don't expect any trouble but air on the side of caution and let others test the waters first.)
Everyone else, hit Software Update, and keep your browsers locked on TiPb for lots more iOS 5 and iCloud coverage!