Exporting 2d linework from blender 2.5
Blender 2.5X still does not feature the excellent dxf exporter Migius wrote for blender 2.49, so I mounted this little workaround to be able to export linework from a blender model to a 2D CAD application such as FreeCAD or LibreCAD (or AutoCAD if you really must...).
It is made of two scripts, a blender addon to export and a FreeCAD macro to import. In blender, install the addon the usual way, then use it from the export menu to export the selected meshes. What will be exported is simply all the edges of the selected meshes in a text file, one edge (2 vertices) per line.
Then, place the FreeCAD macro in your macros folder, then run it, select the exported .txt file, and voila, your objects edges get imported, one compound object is created per blender object. You can then select everything and export to dxf if you want.
The meshes to be exported in blender
The imported linework in FreeCAD
The same linework exported in .dxf fomat and opened in LibreCAD.