Users with a tmpfs /var/run will lose the directory tree state of /var/run at reboot. This rc script will optionally (by default) capture the state of the directory structure in /var/run prior to shutdown and recreate it at system boot.
Alternatively a user can save the state of the /var/run directories manually using service var_run save and disable the autosaving of /var/run state using the var_run_autosave variable, for those paranoid SSD users.