I recently made some screencasts using Camtasia about remixing Flotzam and I then encoded them using Microsoft Expression Encoder using all the default settings. However, the quality was crap compared to the .wmv emitted from Camtasia and I couldn't figure out why. My good man Tim Sneath pointed out to me there's a video setting in Expression Encoder called "Screen Encoding" that is optimized for screencasts. Sure enough I used that setting and had much better results. I then uploaded them to Silverlight Streaming as explained in this post.
A search on the web to find out if anyone else has stumbled on this uncovered this post by Jon Udell, who turns out to be a colleague of mine. Small world.