How do I remove the shutdown confirmation menu?

For 11.10

Run dconf-editor
(either Alt+F2 or from terminal, must be installed first)

/org/gnome/gnome-session/

uncheck "logout-prompt"

I still haven't found a way to return restart to the menu and suppress that confirmation.
(thanks for the edit fossfreedom)

Run gconf-editor
(either Alt+F2 or from terminal)

/apps/gnome-session/options

uncheck "logout_prompt"

/apps/indicator-session

check "suppress_logout_restart_shutdown"

This will remove the annoying dialog in releases preceding Oneiric Ocelot.