Yesterday news spread of Adobe Flash 10.1 adding GPU acceleration support. Today, ATi has released drivers supporting GPU acceleration.
This update is beneficial to ATi users as it will allow fully smooth playback of high resolution, high definition, videos; Hulu, YouTube, Vimeo, Facebook Video, and others… As browser and flash playback has been CPU dependent in the past the long overdue inclusion of GPU acceleration will be a huge blow against video playback stuttering and choppiness through consistent and high framerate.
Download links:
Without GPU Acceleration | With GPU Acceleration |

Any about ATI Mobility support? I’ve read that the HD 4000 series is supported, but any chance of other mobile ATI chips functioning?
I don’t have a direct answer for you, however, I have a hunch that if one were to use Mobility Modder (http://www.driverheaven.net/modtool.php) to mod the driver it would unlock all standard features. This is the case in a number of other instances, and unless there is a specific hardware feature that the Mobilitys lack, I expect it to work.
Additionally, adobe is working on bringing GPU Acceleration to a lot more stuff, so if Mobilitys don’t support it now, they will very soon.
Check this out for more info:
http://blogs.adobe.com/jnack/2009/11/adobe_sneak_peek_major_gpu_acceleration.html