Again, please, don't judge kernel by its version number. The kernel that RHEL6 comes with has version of 2.6.32, but it's as far from "vanilla" 2.6.32 as Chicago from Seattle. It has tons of patches (with OpenVZ patchet being only about 10% of it). There's a somewhat old comparison about RHEL5 patch set that you can see here: http://openvz.livejournal.com/27592.html
