Apple has released Public Beta 2 for both iOS 10 and macOS Sierra, as both products edge closer to a final release this coming fall.
See also: iOS 10 is a total mess
While these releases seem to be primarily bug-fix releases, there are some new features. For example, the latest iOS 10 beta adds an option to unlock your device and go to the Home screen by just resting your finger on the Touch ID sensor (as opposed to pressing on it).
New in the Public Beta 2 of macOS Sierra is iCloud file syncing, which automatically syncs your Desktop and Documents folder into the cloud. Also present is the ability to unlock your Mac using an Apple Watch running watchOS 3. But you won't be able to use this feature unless you have an Apple developer account, because there isn't a public beta of watchOS 3.
To download the iOS 10 Public Beta 2 over-the-air from your iPhone, iPad, or iPod touch, go to Settings > General > Software Update. To grab the updated macOS Sierra you will need to visit the Updates section in the Mac App Store.
If you've not joined the Apple Beta Software Program and feel like you're missing out, click here to enroll your device in the program.