We have created an next3 and patched e2fsprogs OpenNode / CentOS 5 / RHEL 5 rpms - installable from opennode-test yum repo. Provided next3 kernel module is currently built against RHEL5 OpenVZ kernel used in OpenNode - so installing this next3 rpm package on your CentOS 5 or RHEL 5 host will install also OpenVZ patched RHEL5 kernel and newer e2fsprogs package.
Installation and usage instructions are provided by this howto document: http://opennode.activesys.org/documentation/howtos/next3-snapshots/ There is also simple next3 snapshotting automation script available for use with cron - usage and download link provided in howto document referenced above.
Regards,