Here are some steps to be performed in order to lockdown a gnome ubuntu desktop

Hide filesystem to nautilus

• Open a terminal and execut "ls -1 / | sudo tee /.hidden" Do "sudo chmod a+r .hidden"

Disable CTRL+ALT+BACKSPACE adding the following to xorg.conf

• Section "ServerFlags"

  Option "DontZap" "yes"

  EndSection

Disable all shortcuts

• gnome-keybinding-properties

Disable log-out, swtich user, etc..

• gconf-editor -> apps -> gnome-session -> logout-prompt

Disable "create laucher" from options when right clicking on desktop

• Modify /usr/share/nautilus/ui/nautilus-desktop-icon-view-ui.xml and add hidden="true" to line:

  <menuitem name="New Launcher" action="New Launcher Desktop"/> in this way:

  <menuitem name="New Launcher" action="New Launcher Desktop" hidden="true"/>