As in previous years, following yesterday’s event, Apple has now released the final GM seed for iOS 9 to registered developers. The GM seed is a final “release candidate” and barring any problems found in this version, it is expected to be identical to the final iOS 9.0 release scheduled to be rolled out to the public next week.

Unlike prior beta updates, the GM seed does not appear to be available as an over-the-air update; developers will need to download the GM seed from Apple’s site and update to it manually via iTunes.
Along with the iOS 9 GM Seed, Apple has also already released the first beta version of iOS 9.1 to developers.
The iOS 9.1 beta release notes don’t reveal much new in iOS 9.1, although it appears to include developer-level enhancements for new features introduced on the iPhone 6s and iPhone 6s Plus yesterday, such as 3D Touch and Live Photos. The iOS 9.1 beta continues to support the same devices as iOS 9.0 and registered iOS developers can download the iOS 9.1 beta from Apple’s Developer site.