Yes, RHEL 5.3 has been released.
Red Hat Enterprise Linux 5.3 Now Available with Leading Virtualization Performance and Next-Generation Java and Processor Support Capabilities
Release Notes of RHEL 5.3
[rhelv5-announce] Red Hat Enterprise Linux 5.3 GA Announcement
Primary new features of RHEL 5.3 are,
- Increased scalability of virtualized x86-64 environments
- Support for Intel Core i7 (Nehalem) processors
- Inclusion of OpenJDK
Nevertheless, I didn’t see RHEL 5.3 is available for download in RHN yet. Let’s wait for a while.