If, after installing 10.5.2, you do not have the option to disable the translucent menu in the Desktop & ScreenSaver System Preferences panel, chances are you might have used this previous hint to disable the translucent menu bar.
Taking a hint from that particular hint... reset the value that was set by running this command: Logout and reboot, and the option will appear again.
[robg adds: I had the option in the Desktop panel, but it simply didn't seem to do anything. Running the above Terminal command fixed the problem.]

