The all-new Explore tab presents a continuously-scrolling view of app categories. Each category contains a list of its own top-selling apps and allows users to drill down.
The Explore tab also presents users with a new trending topics display, further enhancing discoverability.
Developers are now free to bundle apps together and offer discounts for users purchasing the entire bundle. In addition, developers can enhance app listings with videos.
Additionally, the company added a new Testflight public beta-testing service for developers. Testflight appears to be a product of Apple's Burstly acquisition.
Finally, iOS 8 introduces a new developer tool called Metal. Metal acts to abstract low-level OpenGL programming, allowing developers to more quickly write 3D apps.