While Red Hat Enterprise Linux 6.0
is available for those focusing upon new RHEL installations or those system administrators looking for a major upgrade, Red Hat has just announced the release of Red Hat Enterprise Linux 5.6 as an upgrade to RHEL5.
The Red Hat Enterprise Linux 5.6 release continues to build upon the KVM virtualization foundation that's been building up in RHEL5/RHEL6 with this 5.6 build upgrading against libvirt 0.8.2, enables sVirt for integrating SELinux and virtualization technologies, introduces the virtio-serial driver, adds vmchannel support to RHEL5.6 running on RHEL6 hosts, and much more.
Besides all the virtualization love, Red Hat Enterprise Linux 5.6 also has Anaconda installer improvements, updates to the EXT4 file-system support, and ships with the Linux 2.6.18-238.el5 kernel.
More information on the general availability of this enterprise Linux distribution update can be found in its mailing list announcement
or all of the really good details can be found in the RHEL5.6 release notes