Just today, Apple has released the second beta following the original release a few weeks back at WWDC 2017. The new update fixes a lot of bugs, it also looks like (from the release notes) a new feature related to the AVRouteDetector.
Looking for a full change log?
9to5Mac have published the full change log over in their post for iOS 11 beta 2.
iOS 11 was released earlier this month, on 5th June at Apple’s annual WWDC developers conference, the new software added a lot of new features, including a new redesigned App Store, AirPlay 2 with support for full multi-room audio and a whole host of improvements for multi-tasking on iPad.
Source: 9to5Mac (change log)