Promising a 40% greater rendering efficiency, Apple today announced their Metal development platform along with Metal for Mac.
"Metal is a core graphics technology that gives apps near-direct access to the GPU. This means faster and more efficient rendering performance across the system," said Apple.

Yes, in its simplest form it's a lot like ATI's Mantle technology. In fact, the names are also quite similar to one another.

During today's presentation at WWDC, Apple brought up on stage Epic's Billy Bramer, the lead programmer on Fortnite. Bramer remarked that Epic was seeing a "70% reduction in CPU use versus OpenGL." 2K, Unity, and Blizzard are also working on projects using the "Metal for Mac" program. A Metal for Mac beta is actually a part of today's "El Capitan" update for OS X and can be used by developers.