TechPowerUp reports AMD's upcoming Catalyst 14.1 beta will include the Mantle and TrueAudio runtime environments. You can expect this driver later this month, perhaps as soon as this week.
Mantle promises "great" performance improvements in Battlefield 4, the only AAA game that we know of, to make use of the API. Mantle support was expected to be added to the game as an update around this time, but DICE' plans fell off the track with publisher EA coming down hard on the studio for shipping a game that's riddled with bugs. DICE will most likely have to fix most of its bugs for the retail DirectX 11.1 game, before EA allows it to toy with updates that add support for new and experimental APIs, let alone expansion packs. In related news, Catalyst 14.1 Beta will introduce additions to its frame-pacing fix, that will soon support Ultra HD displays, and Eyefinity setups on non-XDMA (pre R9 290 series) GPUs.