I don't know if this is helpful to others, or even if it is the best way to go about creating a site map. However, I was able to export a Vignette Portal site as a CAR, then use XSLT to create a site map from the component.xml file.
The XSLT walks the menu-list elements in the component.xml. Permissions are not considered, but if a user clicks a link from the site map to which they don't have access, Vignette does not show them the page.
I've attached the XSLT and a batch file that will run the transform using Apache Xalan.
