iOS 5 Beta 4 is now available for deveolpers to download. This is the first iOS update that downloads and installs over the air. Anyone who has iOS 5 Beta 3 can go to Setting> Software Update and download and install the update without connecting the device to a computer.
This update will not install on jailbroken devices, according to the iPhone Dev Team.
The new beta version adds Documents & Data to the list of services supported by iCloud. People are reporting that some portions of iCloud data syncing are now active. Apple appears to be putting the final touches on iCloud for iOS with this beta release.
iOS 5 will be released this Fall to the public.