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, modify the
following lines in your default /etc/yum.conf (yum-2.0.8-2.centos3):

before (fasttrack disabled by default):
#between point release supported updates
#[fasttrack]
#name=CentOS-$releasever - Fasttrack
#baseurl=http://mirror.centos.org/centos/$releasever/fasttrack/$basearch/
#gpgcheck=1

after (fasttrack enabled):
#between point release supported updates
[fasttrack]
name=CentOS-$releasever - Fasttrack
baseurl=http://mirror.centos.org/centos/$releasever/fasttrack/$basearch/
gpgcheck=1

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

https://www.redhat.com/archives/nahant-list/2006-April/msg00001.html