ATI Stream support:

With the release of ATI Catalyst 8.12 users can unlock the potential of accelerated applications enabling ATI Stream technology for millions of ATI Radeon™ graphics processors worldwide
ATI Stream harnesses the tremendous processing power of the graphics processing unit (GPU) for high-performance, data-intensive computations over a wide range of scientific, business and consumer applications.
ATI Stream enables the hundreds of parallel cores inside AMD graphics processors to accelerate general purpose applications.  These capabilities will allow ATI Stream-enabled programs, for a variety of different tasks and from a growing number of software vendors, to operate with optimized performance or with new functionality.
The CAL (Compute Abstraction Layer) is now include in the Catalyst driver package. CAL is the enabling component for ATI Stream 
 

ATI Stream application:  ATI Avivo Video Converter

Using ATI Stream technology, owners of ATI Radeon™ HD 4800 Series and ATI Radeon™ HD 4600 Series of graphics cards can take advantage of this video conversion tool (found in Catalyst Control Center Basic View) to achieve incredible performance levels in video transcoding.
ATI Catalyst Control Center – Noise reduction for progressive video content:

This release of Catalyst™ introduces a new advanced video quality control:  Noise Reduction for progressive video content, which removes ghosting artifacts while preserving details of the original video.  The slider control can be found in the All Settings page of the Avivo Video tab found in the Catalyst Control Center.    

Performance improvements:

• Catalyst 8.12 Preliminary Performance Notes
• Crysis + 2-7%
• Crysis Warhead + 2-3%
• Devil May Cry 4  + 1-6%
• Far Cry 2
• + noAA scores are fixed for Crossfire configs; this is worth +20% on slower cards, and as much as 70% on faster ones
• + 5-10% gains when AA is enabled
• FEAR + 2-6%
• Left 4 Dead + 2-4%
• Lost Planet Colonies + 3-10%, mostly in Area 2
• Prey + 2-5%
• STALKER Clear Sky + 5-10%, primarily on Crossfire configurations

To be released soon.