Apparently, releasing new Catalyst drivers and hotfixes simultaneously is a new thing at AMD. We've gotten a repeat of the 10.10 release, this time with a Catalyst 11.1 driver and an 11.1a hotfix both showing up on AMD's website at the same time. You can grab the 11.1 release from the usual place, while the hotfix is available from this knowledge base entry.
What's new this time? As far as the vanilla Catalyst 11.1 release goes, AMD has taken the revamped Catalyst Control Center out of beta and included it as the new default. The firm has also added support for OpenGL 4.1, and it claims improved performance when F1 2010 and Left 4 Dead 2 are run without antialiasing or anisotropic filtering enabled on some high-end 5000- and 6000-series Radeons. (I'm not sure who'd ever run L42 without AA or AF on such cards, though—that game can run smoothly with the detail maxed out on much slower GPUs.)
Meanwhile, the Catalyst 11.1a hotfix purportedly brings further performance improvements for Radeon HD 6800- and 6900-series cards in "a number of applications," although AMD doesn't say which ones. Also in store are new tessellation controls in the Catalyst Control Center, plus the following updates to Catalyst AI texture filtering:
- The Quality setting has now been improved to match the High Quality setting in all respects but one; it enables an optimization that limits tri-linear anisotropic filtering to areas surrounding texture mipmap level transitions, while doing bilinear anisotropic filtering elsewhere. This optimization offers a way to improve filtering performance without visibly affecting image quality
- The Performance setting has also been updated to address comments about the sharpness of the default Quality setting causing shimmering in certain cases. It now provides a smoother filtering option that eliminates most shimmering while preserving the improved detail provided by anisotropic filtering.
That's all, folks—enjoy the two installers. If you're looking for more in-depth release notes, you can find those here.