This package contains the files needed to do a yum update as a cron job. They were introduced in yum-2.6.1-0.fc5 but have been left in FC6 in favor of yum-updatesd. Install this package if you want automatic updates via a nightly cron instead of using the latest method with yum-updatesd daemon.
Generally yum-cron is more suitable for servers and yum-updatesd for desktop users, and that's why it is still available.
The corresponding cron job are enabled and disabled like any other daemon:
$ sudo yum chkconfig yum-cron on
$ sudo service yum-cron start
With the previous couple of commands the file /etc/cron.daily/0yum.cron will be daily executed at the scheduled time.
