The Quick Launch Toolbar has a "Show Desktop" icon that minimizes/restores
all open windows.
If you want a shortcut that displays the contents of the desktop in an
explorer window,
then create a shorcut that points to %userprofile%\desktop
That will only display the icon that in the current user's desktop folder.
If you want access to the desktop contents that originate from the All Users
desktop,
you'll have to use a 2nd shortcut that points to %allusersprofile%\desktop
If you want multiple accounts to have this functionality,
then right click on My Computer and choose "Properties"
In the System Properties window, click the "Advanced" tab
and click the "Enviroment Variables" button.
Under the "System variables" section click the "New" button.
Enter MyDesktop as the "Variable name".
Enter %userprofile%\desktop as the "Variable value".
Click "OK"
Click the "New" button, again.
Enter AllDesktop as the "Variable name".
Enter %allusersprofile%\desktop as the "Variable value".
Click "OK"
To use this, the users just have to create a shortcut that points to
%MyDesktop%
and a 2nd one that points to %AllDesktop%
Of course in solutions 2 and 3, the second shortcut is only needed if the
users need access
to the All Users desktop only if it's being used.
which ever method you use, the shortcut(s) created can be dragged onto the
Quick Launch Toolbar for easy access.