Please post links to screenshots and/or insights of this vector app. We must learn from others.
Dia is a structured diagrams program similar in purpose to MicrosoftVisio. It is not currently available in a native windows (GDI) version, only as ported GTK application.
The real strength of Dia is that it has a good collection of templates and preset shapes which make it easier to create Diagrams quickly. With tools that make it easy to manage large collections of clipart and the clones functionality already in Inkscape it should be possible to provide many of the same advantages to Inkscape users.
Dia uses a Controlled Single Document Interface (CSDI) similar to the GNU Image Manipulation Program and Sodipodi.
Dia is written in C and has support for plugins written in Python.
Dia makes use of XSLT which hopefully Inkscape could share. Dia also has support for importing various file formats and it would be excellent if there were some way to share these libraries or have a shared infrastructure for vector graphics the similar to how there is the generic gdkpixbuf for raster graphics.
Freshmeat Project Page for Dia
Alan Horkan's Dia gallery (includes screenshots)
GNU General Public License (GPL)