Seema Ramchandani gave a talk back at ReMIX07 in Boston which conflicted with my "Real World Silverlight" talk, so I unfortunately didn't get to see her then. However, she just gave a talk this week in Redmond. In that talk, she showed how redraw regions can be turned on in Silverlight so that you can see how animation, video, property changes etc. all affect how large an area Silverlight attempts to redraw. You get color-coded regions that show updates in real time.

The setting, which she covered in her blog back in October is:

  agControl.settings.EnableRedrawRegions = true;

Set that in your javascript after the control is created. 

This can be an valuable tool for debugging complex performance issues in our Silverlight applications.