A new batch of WHQL-certified Catalyst drivers is out for Radeon graphics cards, and it looks like AMD has really packed in the performance improvements.
First, let's get the download links out of the way. You can grab the new Catalyst 14.9 WHQL drivers here in 64-bit form and here for 32-bit versions of Windows. (A Linux release is also available here.)
According to AMD's release notes, these drivers include general performance improvements for Batman Arkham Origins, Battlefield 4 (Mantle mode), BioShock Infinite, Company of Heroes 2, Crysis 3, Murdered Soul Suspect, Plants vs. Zombies, StarCraft II, Star Swarm (Mantle mode), Thief (Mantle mode), Tomb Raider, Watch Dogs, and Wildstar. Phew. The improvements are mostly centered on the Radeon R9 290 series, and they're counted over the Catalyst 14.4 release, which was the last WHQL-certified update.
The 14.9 Catalysts enable multi-GPU mode in Thief, too, and they improve CrossFire scaling in several titles: Assassin's Creed IV, Batman Arkham Origins, Lichdom, Murdered: Soul Suspect, Plants vs. Zombies: Garden Warfare, and Watch Dogs. Several of the gains fall in the 70-93% range, which counts as less of a performance optimization and more as... you know, scaling actually working as it ought to.
Also in this release are a number of improvements for Eyefinity multi-display configs: better support for mixed resolutions, new alignment controls, and a "One-Click Setup" feature. That's in addition to new color-management controls that apply to single-display configs.
Check out the full release notes for more details as well as performance numbers and a list of bug fixes. As always, remember that the quoted performance figures are best-case scenarios—your own mileage may vary.