The local7 facility is used to write into the /var/log/boot.log file.
But since the Fedora core 4, the system has been disabled waiting for a new generation system which does not seem to be available yet (see this bug report and this one)
A quick way to fix the empty /var/log/boot.log file, is to edit the /etc/rc.d/init.d/functions file.
Into the success, failure, passed and warning functions, you can add a line like the following, just before the return instruction:
/usr/bin/logger -p local7.info "$1"
It works but each time the initscripts package is updated, it is needed to edit the file ...