Since I usually shutdown to boot my mobile hardware profile, I replace my DVD drive with an extra battery when the computer is powered down.
I had forgotten that the icon was missing until Chuck Chopp told me that he discovered how to get it back.
Chuck had be using the Add/Remove Hardware Wizard to remove the device, which would eventually give him the option to enable the system tray icon, but he finally came up with the following elegant fix:
%SystemRoot%\System32\RUNDLL32.EXE shell32.dll,Control_RunDLL hotplug.dll
I created a shortcut on my Start menu to run this command. When I run it, I receive:
which allows me to check the Show Unplug/Eject icon on the taskbar.