After upgrading from 13.04 to 13.10, holding Super no longer brings up the help overlay. Holding Super worked before upgrading. Tapping the Super key still brings up the HUD, and holding it down still brings up the Launcher and after a second or so shows the numbers on the applications.
In Compiz Config Manager, under Ubuntu Unity Plugin -> Launcher, the Key to show the Dash, Launcher and Help Overlay is set to Super.
Under Ubuntu Unity Plugin -> General, "Enable Shortcut Hints Overlay" is checked.