This Mac Pro has dual SuperDrives both upper/lower drivebays, which could be independently ejected via the menubar under 10.5. After upgrading to 10.6, the upper drive no longer responds to the menu command. The eject button has to be hand-pressed with a paperclip to open (but a loaded disc can still be ejected via dragging to the trash).
Sounds like a simple setting somewhere, except I can't find it to re-enable the second drive.
