Preview at WWDC likely in June, followed by September launch.
Apple Releases iOS 5 Beta 5 to Developers
In a surprise move, Apple has released iOS 5 Beta 5 (build 9A5288d) to developers on Saturday. Apple typically releases new developer seeds on weekdays. Alongside the iOS 5 beta 5 release is Xcode 4.2 Developer Preview 5, iTunes 10.5 Beta 5 and Apple TV Software beta 4.
iOS 5 Beta 5 is available as an over the air update, but according to the release notes, users must first erase all content and settings by choosing Settings > General > Reset > Erase All Content and Settings. Apple recommends backing up your device using iTunes 10.5 Beta 4 or through iCloud prior to installing iOS 5 beta 5, and subsequently restoring. That said, some users have been able to upgrade fine without going through that process.
BGR posts the release notes, which details some fixes, but no major new features. We're looking into what other changes may have occurred.
Hearing Aid Mode is said to be new in iOS 5 Beta 5:
Over the air update from Beta 4 to Beta 5 is 128MB.
NatesTechUpdate offers this video which goes over some of the new findings in iOS 5: