Just a few more links that I remembered seeing months ago.
http://lx-viewer.sourceforge.net/ lx-viewer claims to open DXF (via the non-free opendwg libs) and save SVG 1.0. And this reminds me of one of the truly awesome thing about the STDIN/STDOUT scripting support. There are comercial packages to make conversions between just about any format. In no time flat just about anyone could write an *.inx file to hook one of these up to Inkscape. It would be much better if there were a free and open alternative, but in a pinch an outlet exists.
http://mail.python.org/pipermail/pythoncad/2004-September/000301.html Linux-CAD lists might be a good place to ask around before anyone starts writing. It sounds like there are some projects of this nature brewing in other places as well. This fact underscores the need.
http://www.inkscape.org/cgi-bin/wiki.pl?CadInteroperability It looks like there is already a page on the wiki for this discussion.
Aaron Spike