Today at WWDC 2011 Apple demoed iOS 5 & Mac OS Lion also a new service iCloud has been announced. In order to support iCloud service Apple has updated iTunes to iTunes 10.3 for Windows & Mac. As announced at WWDC 2011 users will be able to upload all the contents on cloud will be instantly accessible on all idevices.
iTunes 10.3 gives you new ways to get your music, apps, and books from one device to another — wirelessly and without syncing. And the iBookstore comes to iTunes on your Mac or PC for an unabridged browsing and shopping experience. With iTunes, even getting your entertainment is entertaining.
Download iTunes 10.3 Beta (Direct Download Link)
Developers updating their iOS device to iOS 5 will require iTunes 10.5 Beta to activate and sync their iPhones. Download iTunes 10.5 Beta from here