I guess that you upgraded from 10.04 to 12.04.
At Ubuntu 12.04 yes , the startup applications are hidden. Is not a problem or a fail that the catalog is empty. Its more like a security "valve" so users not delete any essential startup application and corrupt the system.
Here is a way to reveal all the startup applications in Ubuntu 12.04.
Be careful , because the following command will reveal ALL the startup applications.
Open a terminal and give this command
sudo sed -i 's/NoDisplay=true/NoDisplay=false/g' /etc/xdg/autostart/*.desktop
Then open again the startup applications and I'm certain that the list will have grown.