As part of iCloud, iTunes in the Cloud takes what you buy on iTunes on one device and pushes it to all your other devices, wirelessly and without syncing.
What's new in iTunes 10.5
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.
You can get the update by selecting Software Update from the Apple menu at the top left of your screen or from the link below.
Windows x32
Windows x64
Mac