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-3, add this entry
into your /etc/yum.conf file and it will be enabled.

name=CentOS-3 fasttrack

See this upstream mailing list post for more info on fastrack: