“Almost exactly two weeks after the release of Red Hat
Enterprise Linux (RHEL) 4.9, the CentOS project has completed
CentOS 4.9. The RHEL clone was released relatively soon after its
RHEL equivalent because, like the original, CentOS hasn’t provided
any updated installation images; such images are typically made
available for minor releases, sometimes also called service packs,
of RHEL and CentOS.“This is due to the age of the RHEL 4 family, as Red Hat plans
to discontinue the regular support for this distribution in
February 2012 – seven years after RHEL 4.0 was first
introduced.”