My answer, that you could repurpose some of the parts of a SketchFlow prototype, was not as complete as I’d have liked. So I did a little experimenting this morning and confirmed that you can take a SketchFlow screen essentially* as-is and bring it into a Silverlight 3 project and use it for building the final version of the application. SketchFlow screens are implemented as a Silverlight UserControl class, and all of the UI elements are just XAML.
I also updated the completed version of my Silverlight 3 / Expression Blend 3 demo project to include an example of a hand-drawn sketch repurposed from a SketchFlow screen. You can download the updated version of the demo, along with my slide deck, here.
So in addition to the advantages of rapid prototyping and super-simple communication and collaboration between the design team and project stakeholders, the ability to easily repurpose content created as part of a SketchFlow prototype is a compelling reason to take a look at this cool tool.
* – I say “essentially” because I did find one little issue with just grabbing the .xaml and codebehind files, which is that you will need to modify the x:Class attribute on the UserControl element to match the namespace of the target project when you copy it into the target project. Otherwise you will get a compilation error when you try to build the project, "InitializeComponent is not declared" If you see that error, check your namespace…it’s often the cause of this error.