Apple also released iOS 12 Developer Beta 2.
macOS Mojave brings a mix of under-the-hood changes, like APFS support for Fusion drives and hard drives, and more visual changes. The biggest feature in the second category has to be Dark Mode, a UI option designed for working more comfortably with less lighting. Developers and creative types seem particularly enamoured with it.
Apple Developer Connection
Developers can register their devices for the Mojave beta at the Apple Developer Connection. If you’re already participating in the developer beta program you’ll see the update in Software Preferences > Software Update on your Mac.