Microsoft just launched their 2 very tied to each other Silverlight and Expression software. The update seems to be giving more tools with HD video streaming, sketchflow which is for UX (funny adobe launched Catalyst with the same purpose not so long ago) and some small other goodnesses. I have seen some sites using Silverlight, I never really was amazed by them.
The ABC HD player which is flash based is for me the state of the art as video player goes.
You also have to consider if Silverlight is the reason why Microsoft is so muted about the HTML5 video tag.
Anyway you can see the amazing power of these tools yourself on seethelight.com