A short while ago, Apple released iOS 5 beta 3 for iPhone, iPad, iPod touch and Apple TV. Along with a new pre-release beta of iOS 5, Apple has also released the next developer beta of iTunes, for both Windows and Mac computers. iTunes 10.5 beta 3 is now available for download to all developers enrolled in the Developer Program.
A little heads up for you though, if you are running iOS 5 beta 2, please note that iTunes 10.5 beta 2, which was released alongside it, does not have support for iOS 5 beta 3. Meaning that before you upgrade your device that is running iOS 5 beta 3, you first need to back it up with iTunes 10.5 beta 2, then upgrade it to iOS 5 beta 3 and then restore the data on your device from the backup you previous made, through iTunes 10.5 beta 3.
One of the great features that iTunes 10.5 beta 2 brought, particularly for Mac, was wireless syncing of devices running iOS 5 beta 2, with itself. Note that Mac OS X 10.6.8 is a pre-requisite for wireless iTunes syncing to work. With iTunes 10.5 beta 3, your iOS 5 beta 2 running device won't sync wirelessly, you'll need the latest beta of iTunes, to wirelessly sync your iOS 5 beta 3 running device.
So if you are enrolled in the iPhone Developer Program, you can access the iTunes 10.5 beta 3 download files from the Developer Portal. If you're not a developer, you'll just have to sit with your fingers crossed until someone re-uploads these iTunes 10.5 beta 3 download files to file sharing websites on the internet.
Developers, enjoy!
UPDATE: Direct download links of iTunes 10.5 beta 3 for Windows and Mac posted.