The AMD Catalyst™ 12.2 Preview includes all of the features found in AMD Catalyst™ 12.1, plus additional fixes that are not included in the AMD Catalyst 12.1 release.
Please note that AMD Radeon HD 7900 users should keep using the 8.921.2 RC11 driver found here (the 12.2 preview does not supported the AMD Radeon HD 7900 Series): http://support.amd.com/us/kbarticles/Pages/RC11Driver.aspx
Feature highlights of the AMD Catalyst™ 12.2 driver:
AMD Eyefinity 2.1 technology enhancements
Additional resolution support: Users can now choose from a larger set of resolutions when running AMD Eyefinity
Dynamic Configuration Changes: Switching between different display configurations will occur automatically when physically plugging/un-plugging displays
HydraVision™ enhancements: The Windows Task bar can now be moved and resized based on users preference
Profile Manager improvements: Increased support for Display Groups (including 5x1) and Extended configurations within the Profile Manager