I just checked the download page at Red Hat. The current release is still at 6.3. RHEL 6.4 is in beta. By the way, the 5.9 GA release was about a month ago and is in the "Release channel"... [by toracat]
on 02/10/2013 – Made popular on 02/10/2013
Following last week's release of Red Hat Enterprise Linux (RHEL) 7, the focus of many users will now undoubtedly turn towards CentOS and other RHEL clones - in expectation of an early delivery of a "gratis" system based on RHEL 7.
We are currently building and testing our CentOS-6.6 release. It
normally takes about 2-4 weeks for us to get a full point release out.
We can not release updates that are based on 6.6 until we get 6.6 out.