There is now a SVN branch for the dbus scripting work:
https://inkscape.svn.sourceforge.net/svnroot/inkscape/inkscape/branches/gsoc...
The build system should do everything automatically if you have a reasonably recent DBus installed (Ubuntu users should already have this.)
If your Inkscape executable is not in the standard place (/usr/local/bin/inkscape) you might have to modify src/extension/dbus/org.inkscape.service.in for Inkscape to start automatically when requested. This will be set automatically soon, but for now is hardcoded.
Almost all functions are implemented but a couple are still stubs. A few are under active development and will crash Inkscape, especially ones that return lists. Most of the functions are stable, however. See /src/extension/dbus/document-interface.cpp for details.
Let me know if you have any problems making or running the test script given in the documentation.
Thanks for your interest,
-Soren