Software User Interface Design Tool

For all you software developer types, there's a cool new GUI design tool coming out soon. Here's a snippet from the web site:

Caretta Software - GUI Design Studio: "GUI Design Studio is a graphical user interface design tool for Microsoft Windows that you can use to rapidly create demonstration prototypes without any coding or scripting.

Draw individual screens, windows and components using standard elements, connect them together to storyboard operational workflow then run the simulator to test your designs."

It looks good for Windows applications and could also be used for web development though I don't think it's intended for that.