The Tech Report has written a report about GPU accelerated video with Flash 10.1 beta, you can check it out over here.
This Flash 10.1 beta is just a first step, and obviously both Adobe and the various GPU makers have some work to do yet. GPU acceleration is still pretty fragile, and although AMD and Nvidia seem to have a good handle on the basics, Intel's GMA 4500MHD currently doesn't perform very well. Even so, most of the initial performance indications are positive. One can't help but be encouraged by watching an Atom/Ion-based system playing back Flash video with fluidity.
Heck, I'm not even sure exactly how to feel about this development. For so long, Adobe and Flash have been objects of derision for many PC enthusiasts, because really, how could Flash not be GPU-accelerated? Now that it's happening, I suppose I feel more relief than gratitude, like a captive being released from a terrible ordeal—only, you know, in a really muted and low-stakes way.