CentOS 5.9 is a Linux distribution built from the source code of the recently-released Red Hat Enterprise Linux (RHEL) 5.9. New features: the UOP added native MySQL support to Postfix, you might consider moving from the postfix-mysql package from the centosplus repo to this package if you are using the centosplus package only for MySQL support; java-1.7.0-openjdk (Java 7) support has been added in CentOS-5.9, java-1.6.0-openjdk (Java 6) is also still available and most things java in the distribution still use Java 6; ant17 (Ant 1.7.0) has been added to CentOS-5.9, the older ant (Ant 1.6.5) is also still available; Microsoft Hyper-V drivers have been added to allow CentOS to be more efficient as a virtual machine when installed on Microsoft Hyper-V server.
 
About CentOS
CentOS as a group is a community of open source contributors and users. Typical CentOS users are organisations and individuals that do not need strong commercial support in order to achieve successful operation. CentOS is 100% compatible rebuild of the Red Hat Enterprise Linux, in full compliance with Red Hat's redistribution requirements. CentOS is for people who need an enterprise class operating system stability without the cost of certification and support.