http://lists.centos.org/pipermail/centos-announce/2011-April/017282.htmlWe are pleased to announce the immediate availability of CentOS-5.6 for
i386 and x86_64 Architectures.
CentOS-5.6 is based on the upstream release EL 5.6 and includes
packages from all variants including Server and Client. All upstream
repositories have been combined into one, to make it easier for end
users to work with.
Upgrading from CentOS-5.5 ( or CentOS-5.0 / 5.1 / 5.2 / 5.3 / 5.5 ):
If you are already running CentOS-5.5 or an older CentOS-5 distro, all
you need to do is update your machine via yum by running :
Running 'yum list updates' before doing the update is recommended, so
you can get a list of packages that are going to be updated. To check
you are indeed on CentOS-5.6, run : 'rpm -q centos-release' and that
should return: 'centos-release-5-6.el5.centos.1'