Apple has made the final GM version of iOS 6 available to registered developers. The release comes after Apple announced that iOS 6 will be made available as a free public download next Wednesday, September 19th.
The Xcode 4.5 GM has also been seeded in the Dev Center. All iOS developers can start downloading the iOS 6 GM and new version of Xcode now. The version of iOS 6 that ships next week will be the exact same as the GM that Apple just released.
Refer to Apple’s website for a rundown of the new features in iOS 6.