"Garcon is an implementation of the freedesktop.org menu specification replacing the former Xfce menu library libxfce4menu. It is based on GLib/GIO only and aims at covering the entire specification except for legacy menus."
http://archive.xfce.org/src/libs/garcon/0.1/garcon-0.1.0.tar.bz2
I've committed xfce-base/garcon to tree, nothing is using it yet, but soon as something starts using it we should too(?)