Just a little while ago Apple pushed out iOS 5 Beta 6 for iPhone 4, iPhone 3GS, iPad 1st Gen, iPad 2, iPodTouch 3G & iPodTouch 4G. Keep in mind that this is only for developer who are part of Apple iPhone Developer program. For those who already installed iOS 5 Beta 5, can get iOS 5 Beta 6 via OTA. To install OTA, you must first erase all content and settings on your device by choosing Settings > General > Reset > Erase All Content and Settings. Over the air software update can be initiated on devices running iOS 5 beta 3 and later by choosing Settings > General > Software Update.
Along with this, Apple also pushed out new beta version of iTunes 10.5 Beta 6 (This is required to Sync your iOS device running iOS 5 beta 6) & Xcode.
Download iOS 5 Beta 6, iTunes 10.5 Beta 6