administration.png, file-manager.png, network-config.png, apacheconf.png, logviewer.png, gnome-networktool.png, system-floppy.png, serviceconf.png, postscript-viewer.png, applets-screenshooter.png, panel-notification-area.png, administration.png, file-manager.png, network-config.png, apacheconf.png, logviewer.png, gnome-networktool.png, serviceconf.png, postscript-viewer.png, web-browser.png, tsclient.png, applets-screenshooter.png, xsane.png in /usr/share/icons/gnome/48x48/apps/ are provided by both packages.
The problem obviously still remains. Affected package versions x11-themes/gnome-icon-theme-2.16.1 and x11-themes/ximian-artwork-0.2.29.0.6.3. It is not a good idea to unmerge gnome-icon-theme in order to install ximian-artwork, as there are some icons only contained in the former one such as gnome-lock-screen, gnome-logout, start-here, gnome-shutdown and a lot more.
ximian-artwork removed from tree due bug 152939