The visible effect of this is that recent versions of tomboy no longer shut down when trying to log out, since dbus-sharp doesn't pass that signal along. The referenced ubuntu bug report explains in more detail and links to patches from dbus-sharp upstream.
+*dbus-sharp-0.7.0-r1 (21 Jan 2012) + + 21 Jan 2012; Pacho Ramos <pacho@gentoo.org> +dbus-sharp-0.7.0-r1.ebuild, + +files/dbus-sharp-0.7.0-fix-signals.patch, + +files/dbus-sharp-0.7.0-fix-signals2.patch: + Fix signals not being passed to tomboy properly, bug #387097 by Hans de + Graaff. +