For the first time OpenVZ released these days a new class of patches for Linux kernel.
The new patches available for Red Hat Enterprise Linux 5 (both x86 and x64 versions), has been developed in a way it’s compatible with Xen patches, which RHEL already offers out of the box. In this way users can decide which virtualization approach they prefer, or even run both of them in parallel.
In any other case OpenVZ and Xen patches would have been incompatible with each other obliging users to choose one.
The new patches are available here.