Following weeks of delay, AMD announces they've found a major bug in the upcoming Catalyst 14.1 beta driver that prevented them from releasing the driver to the general public. The Mantle driver was supposed to arrive in tandem with DICE's Battlefield 4 update on Thursday but it looks like you may have to wait at least another day before you'll be able to download the new driver.
AMD now tells us that their teams have been working overnight to fix the driver, and should have their next status update for us by mid-afternoon EST (New York time), later today. That update doesn't necessarily mean a driver release at that point in time, and so AMD might be forced to label it Catalyst 14.2 beta, keeping up with its calendar-based driver version naming. Catalyst 14.1 beta was expected to ship the first public distribution of Mantle, AMD's ambitious 3D graphics API to rival Direct3D and OpenGL.
AMD also mentioned a 24 hour exclusive period for press to evaluate the driver before public release, so it looks like your download will be at least 36 hours away.