Red Hat has announced the availability of RHEL 5.8. You can find more information on this here:
- Release Notes
- Technical Notes
- Kernel update page including a list of bug fixes
- kernel level: kernel-2.6.18-308.el5.
From a mainframe perspective this has been a pure bug fix release. There is one important feature update though. Red Hat included an update to the additional gcc44 package enabling complete z196 support. As a dependency the binutils220 package will be installed as well. With those two packages you can start building binaries targeted for the z196 with the -march=z196 option or at least tune for it with options like –march=z9-109 -mtune=z196.