iOS 7 GM has been released to those registered with the Apple Developer Program. The GM (Golden Master) build is the final release version, which will become available to the general public at a wider release next week.
Devices supported by the final iOS 7 build include the iPad 4, iPad 3, iPad 2, iPad mini, iPhone 5s, iPhone 5c, iPhone 5, iPhone 4S, iPhone 4, and iPod touch 5th gen.
Downloading iOS 7 GM must be done through the iOS Dev Center, where IPSW can be found and installed directly through iTunes. There is currently no OTA (over-the-air) update available to update from iOS 7 beta 6 to the GM build, and due to the nature of GM builds it is unlikely an OTA will become available. Thus, users will have to update directly to the GM manually with IPSW firmware, wait for the wider release, or downgrade back to iOS 6 while it remains possible.
Along with the GM build, Apple is also soliciting developers to submit their apps for iOS 7.
For iPad, iPhone, and iPod touch users who are not developers, iOS 7 will be released on September 18 as a free download. Users who are purchasing the new iPhone 5s or iPhone 5c will find iOS 7 preinstalled on those models.