The second beta version of iOS 8.4.1 has been released to users in the registered developer program. The 12H318 build arrives a few weeks after the first beta of iOS 8.4.1, and the public release of iOS 8.4
No notable features or changes are mentioned with iOS 8.4.1 suggesting the final release will be a simple update focused on bug fixes, security enhancements, and other minor changes to the operating system for iPhones, iPads, and iPod touch.
Users who are eligible to receive the beta build can find it available now from the Software Update mechanism in iOS Settings. IPSW files for a manual update can be downloaded from the iOS Developer Center at Apple.com as well.
There is no known timeline for iOS 8.4.1 final release, though typically betas go through several versions before a final version is available.
Separately, iOS 9 betas are available for public beta users and developers, versioned as public beta 2 and developer beta 4. iOS 9 includes a variety of new features and other notable changes, making it a much more significant update when it arrives as a final version later this year in the fall.