An early beta of Catalyst 12.11 for x86/x86_64 Linux is already available from support.amd.com.
As usual, there is no official release notes from AMD for this updated Linux Catalyst driver. However, for the information I happen to know about this new binary blob... There should be some 2D performance optimizations, Red Hat Enterprise Linux 6.3 support, and some other random work, but nothing too breakthrough.
If you missed it, be sure to check out the recent Windows 7 vs. Ubuntu 12.10 benchmarks of the AMD Catalyst driver.