Adobe has released the Flash Player 10 Beta simultaneously for Linux, Mac, and Windows. This version includes performance improvements, new 3D transformations, Adobe Pixel Bender filters, streaming video improvements, and new text layout capabilities.
Websites very likely won’t be taking advantage of these new features until the stable release is out, so Adobe has a page of demos you can try.
Two large complaints about Flash on Linux are fullscreen video and 64-bit support. Neither have been resolved in this release. Playback of fullscreen video (which causes low framerates and high CPU usage) seems to be only slightly improved. I have found that there is a general performance increase.
If you want to try Flash Player 10 you can download and install it yourself, but here are some terminal commands that you can copy and paste to get going quickly: