Apple has just released the sixth beta version of IOS available to developers in May. The sixth beta build number has 9A5302b and is available for developers in the iOS Dev Center or as an OTA software update. Published so far all the betas for about two weeks. Also, developers can download iTunes 5.10 beta 6, which is required for devices with IOS IOS-5 beta 6 to synchronize.
The enclosed change log shows that Apple is a lot of bugs that were still outstanding has been corrected. This covers items such as calendar, icloud, syncing with iTunes over Wi-Fi and Safari. These and any future betas are likely to mainly solve the problems rather than add new features.
If rumors are to be believed, the next iPhone on October 7 in sales. Until now, Apple released the final versions of IOS major updates and a half to two weeks before the launch of a new iPhone. It is obvious that Apple will use this time such a plan. In the meantime there will probably follow one or more betas followed by a so-called Golden Master, which is usually the version that Apple later everyone ban.