Red Hat Enterprise Linux 5.7 Updates Linux Security
From the 'More Secure RHEL' files:
After a little less than two months of beta testing, Red Hat Enterprise Linux 5.7 is now generally available.
RHEL 5.7 hit public beta status at the end of May, and isn't just about bug fixes and driver support. RHEL 5.7 also introduces some new features to RHEL 5.x even as Red Hat pushes and promotes the newer RHEL 6.x branch.
From my perspective the inclusion of OpenSCAP for security is the biggest new feature. OpenSCAP started off (like many RHEL features) as a Fedora feature. Fedora 14 in October of 2010 was the first to include it, providing a way for enterprises to ensure that systems are kept updated and properly configured to prevent exploits.
In addition to OpenSCAP, Red Hat has improved both KVM and Xen virtualization in RHEL 5.7. For Red Hat customers that rely on Xen, RHEL 6.x is not an option, so Red Hat's continued improvements to Xen only happen now on the RHEL 5.x branch. I suspect that for those enterprises that are hesitant (for whatever reason) to fully embrace KVM, they'll be sticking with RHEL 5.x for a long time yet.
RHEL 5.7 also provides some networking and storage improvements, including some new network bridging and autofs features that Red Hat hopes will provide better management of user filesystems.
It's important to remember that even though RHEL 6.x is now out (and has been since the end of November), big mission critical enterprise deployments are slow to move (if at all). The long term support (up to 10 yrs) that Red Hat provides for releases is great, but the continued improvements that make RHEL 5.x a vibrant OS alongside RHEL 6.x means that it's not just on life support, it's real support.