iOS 5 Beta 7 (Update: new iTunes, Apple TV, Xcode, Safari betas too)
Available via OTA,
but not on the developer site yet. Scratch that, it's on the web too now. Thus, check your device!
Apple also updated to iTunes 10.5 beta 7, Apple TV beta 6, Xcode 4.2 and iOS 5 SDK beta 7 and Safari 5.1.1 Update 3. Boy Genius Report has dropped the release notes.