Ubuntu 11.10 introduced a lighter Startup Applications Preferences, composed only from the extra installed apps, like Diodon, Synapse, etc in order to probably facilitate an easy access and understanding of how to enable/disable various apps when the computer starts.
This may seem inappropriate for some of the more knowable users, who want to disable specific default apps/services (like for instance, Bluetooth).
Fortunately, there is a simple solution to enable all the apps in the Startup Application Preferences (accessible via the Session Menu from the top Unity panel): type in a terminal the following commands
sudo sed --in-place 's/NoDisplay=true/NoDisplay=false/g' *.desktop
To return to the previous behavior
sudo sed --in-place 's/NoDisplay=false/NoDisplay=true/g' *.desktop