ezjail is now capable of managing jails in seperate ZFS filesystems and to manage basejail and newjail in seperate ZFS filesystems too.
It is possible to mix non-ZFS jails with ZFS jails as well as using ZFS jails with basejail/newjail in a non-ZFS filesystem.
To create a zfs jail you need an existing ZFS pool, ZFS needs to be enabled in /etc/rc.conf and you have to set at least ezjail_jailzfs in ezjail.conf. To let ezjail manage basejail/newjail in ZFS filesystems to, you have to enable ezjail_use_zfs in ezjail.conf.
To use ZFS support in ezjail, you have to use at least FreeBSD 7-STABLE form after the commit of ZFS version 13 (commited Wed May 20 23:34:59 2009 UTC, http://svn.freebsd.org/viewvc/base?view=revision&revision=192498) of FreeBSD 8-CURRENT. Prior versions of ZFS are _not_ supported.
Creating a ZFS based jail is as easy as using 'ezjail-admin create -c zfs <jailname> <jailip>'.
Using zfs send/receive for archiving is not yet implemented.
Converting non-ZFS basejail/newjail setups into ZFS setups is not handled by ezjail, converting non-ZFS jails into ZFS jails is not yet handled by ezjail but will be possible in the future.
WARNING: ZFS is considered to be an experimental feature in FreeBSD. ZFS support in ezjail is work in progress.