The Catalyst 11.8 Linux driver can be downloaded from AMD.com.
Unfortunately, AMD is still not putting out detailed release notes for their proprietary Linux Catalyst driver builds. Fortunately, Phoronix has you covered. Some of what you can expect to see out of Catalyst 11.8 for Linux x86/x86_64 include the last of the ATI branding being replaced by AMD, updated Ubuntu packaging scripts, and various bug-fixes.
AMD has finally finished re-branding ATI marks to AMD four years after they acquired the company. This re-branding includes renaming the "aticonfig" utility to "amdconfig", but there is a symbolic link between the two so that nothing is broken. There's also ATI reference changes within the installer and AMD Catalyst Control Center Linux Edition (AMDCCCLE).
Among the bug-fixes in Catalyst 11.8 is fixing 2D corruption when using Compiz with RandR 1.3 panning enabled, an X Server crash fix for Unity, blank displays when starting X with CrossFire enabled, and missing display properties for DisplayPort.
That's about it, grab it if you wish. There's also new tests this morning of Catalyst vs. open-source Radeon driver under Linux and a feature look at where the two AMD drivers are at today. Coming up shortly is the four year anniversary of AMD's open-source strategy.