Apple has released iOS 11.1 beta 3 for iPhone, iPad, and iPod touch users who are enrolled in the beta testing programs. Separately, tvOS 11.1 beta 3 and watchOS 4.1 beta 3 are also available for best testing too.
The iOS 11.1 beta 3 software update is available now for developers enrolled in the developer testing program, whereas the public beta testing version is usually soon to follow.
Users enrolled in the beta testing programs can download iOS 11.1 beta 3 now through the Software Update mechanism in Settings app of compatible iPhone, iPad, and iPod touch.
iOS 11.1 focuses on bug fixes and feature enhancements, hundreds of new emojis, re-includes the 3D Touch gesture to access multitasking on iPhone which is missing from the initial iOS 11 release, and will likely include a few new features like Apple Pay Cash.
Additionally, watchOS 4.1 beta 3 and tvOS 11.1 beta 3 are also available for developers and those interested in running beta software on their Apple Watch and Apple TV. Those updates are available through their respective OTA software update mechanisms in Settings as well.
macOS High Sierra 10.13.1 beta 3 has not yet been released for Mac users, but if Apple follows the usual beta release cycle it will debut soon as well.