There is a new channel provided by the upstream provider called fastrack. This channel will have RPMS that are going to be included in the normal update sets (3-4 times per year), but released once a week. These RPMS will normally be bugfix or enhancement updates and not Security updates. Accordingly, CentOS has created a fasttrack (note the spelling difference, it is intentional) repo. This repo will track the upstream fastrack channel. If you would like to use the FastTrack repo for CentOS-4, copy the file CentOS-fasttrack.repo into your /etc/yum.repos.d/ directory and it will be enabled. See this upstream mailing list post for more info on fastrack: https://www.redhat.com/archives/nahant-list/2006-April/msg00001.html