If you launch Software Update, you should see iPod Updater 2006-03-23 pop up. Weighing in at 27.6MBs this update contains both New iPod Software 1.1.1 for iPod and New iPod Software 1.1.1 for iPod nano. Besides the normal group of bug fixes, the main feature being added is Volume Limit, which Apple claims will be mentioned here, although the link currently doesn't work.
Cool. I wonder if it will limit the volume from blaring every time my cellphone rings, or if that bug still works around this fix.