Along with the release of iOS 5 Beta 5 earlier today, Apple released the latest beta version of iTunes, iTunes 10.5 Beta 5.
If you're not going to update your device to iOS 5 Beta 5 over-the-air, Apple recommends you first update via iTunes 10.5 Beta 4, and then update to iTunes 10.5 Beta 5.
Confused? Then read the following release notes: