Finally, it has been posted - Frank Swiderski's Threat modeling tool is now available for free download on MSDN. From the blurb:

The Threat Modeling Tool allows users to create threat model documents for applications. It organizes relevant data points, such as entry points, assets, trust levels, data flow diagrams, threats, threat trees, and vulnerabilities into an easy-to-use tree-based view. The tool saves the document as XML, and will export to HTML and MHT using the included XSLTs, or a custom transform supplied by the user.

http://www.microsoft.com/downloads/details.aspx?FamilyID=62830f95-0e61-4f87-88a6-e7c663444ac1&displaylang=en

:)