From the 'Microsoft Interoperability' files:

Red Hat Enterprise Linux 6.4 (RHEL 6.4) is now generally available after first appearing in Beta back in December of 2012.

Since RHEL 6.x is still in the first phase of its lifecycle, Red Hat is still adding new features. For me the biggest pile that stand out are the new host of Microsoft interoperability features that I wrote about when the beta debuted.

RHEL 6.4 included support for the Microsoft Hyper-V Linux drivers. The idea is that it will enable RHEL to be a beta guest on a Windows Server (and potentially vice-versa). There are also interoperability improvements with Microsoft Exchange in the Evolution email system that Red Hat includes in RHEL.

An updated version of the System Security Services Daemon (SSSD) in RHEL 6.4 now makes it easier to authenticate to Active Directory.

RHEL 6.4 also introduces a new filesystem (as if Linux didn't have enough already..) with the parallel Network File System (pNFS) industry standard.

"NetApp and Red Hat are seeing considerable demand for pNFS capabilities from customers looking to modernize their data center environment to address the extreme requirements around scale, performance and manageability," said Patrick Rogers, vice president, solutions and integrations, NetApp in a statement. "With Red Hat Enterprise Linux 6.4, Red Hat has achieved a significant milestone advancing pNFS client support, which reflects their continued leadership and innovation in enterprise-class open source solutions."

With RHEL 6.4 now out the door, my attention is now going to turn to RHEL 7 which I strongly suspect will be out this year, but we haven't yet seen a public beta.

Sean Michael Kerner is a senior editor at InternetNews.com, the news service of the IT Business Edge Network, the network for technology professionals Follow him on Twitter @TechJournalist.