Comment 1 for bug 137165

I also get the same. I think it is because the statusIcon = gtk.StatusIcon() is in a try block, and may not be being called?

It can be fixed by changing lines 558-566 to:

statusIcon = gtk.StatusIcon()
try:
    # Run the thread which updates the wallpaper
    updater = Updater()
    updater.start()

    # Create the status icon
    statusIcon.set_from_stock(gtk.STOCK_REFRESH)
    menu = gtk.Menu()