When working in SketchFlow for SilverLight 3, the default file name of the test page is called TestPage.html. If this is not what you want, you can easily change it in the main SketchFlow project’s .csproj file. If you open up the <project-name\>.csproj file, at around line 27, you should see a tag called <TestPageFileName>. Change this to the filename you want. In my case I wanted index.html since I was hosting the prototypes on the intranet and wanted a simple url like

http://sketch/

Hope this helps some folks.