We are working on RHEL 5.11 support and will be communicating an early support statement soon detailing what works in the current release. Support will likely be added in a future hotfix which is yet to be defined.
If you are considering adopting RHEL 5.11 please let me know how quickly and what features are driving you to move to 5.11.
Note: while we cannot respond to all comments directly or guarantee that support will be added we do read all comments and use them to help drive our roadmap.