Bubblemark has added a JavaFX version of his bubble animation test that spans now all of the RIA technologies out there. Bubblemark is a great site and has been a great site for comparing animation in the browser. Alexey Gavrilov has kept the site up to date on all versions of Silverlight since when it was WPF/E and it is a nice quick baseline test to check FPS performance across these new vector toolkits and scripting.
My results are very similar to Bubblemarks tests:
JavaFX — 14 fps
Firefox + Flex — 62 fps
Adobe AIR — 62 fps
Firefox + Silverlight (CLR) — 99 fps
Silverlight is not final and is quite light compared to Flex (I wonder if a vanilla Flash9/AS3 export has been done or if it would perform any different), but if Silverlight has a lead on FPS, where FPS is really success of any kit in RIA or vector, then it could be a rough battle. Flash/Flex is really far far ahead due to the browser penetration and the development community but the better performance is always a good indicator of possible success. Plus, Microsoft controls the desktop market and any “benefits” it might give their own kit which includes distribution and performance in preloading or caching.