That's now obsolete. With 13.10 gnome-session-fallback is a transitional package...

		tod222 on Feb 15, 2014 \| parent \| context \| favorite \| on: Losing graciously That's now obsolete. With 13.10 gnome-session-fallback is a transitional package. The new package is gnome-session-flashback, so the command is now: apt-get install gnome-session-flashback