Adobe has been developing GPU acceleration in recent builds of Flash player, and the Stage Video feature in the 10.2 release now offloads the whole video rendering pipeline to the GPU, so not only is H.264 decoded in hardware, but other adjustments such as color conversion and scaling are managed by the GPU.
Support for full-screen mode with multiple monitors has also been improved on, which is good news for folks who run multiple monitors at one go.The latest release is also the first that will only be available for Intel-based Macs. The last version of Flash to support the PowerPC platform will be the 10.1 series, so if you have a PowerPC Mac running Leopard or Tiger, Adobe you will not be able to run Flash 10.2.
You can download it from here.