Very interesting to see progress of ZFS in FreeBSD, comitted in FreeBSD 7 ( will release in 2007). This excellent job done by Pawel Jakub Dawidek with collaboration with opensolaris for suitable patch .
Many feature that ZFS offer that make me hard to blink till see last pages of presentation
Pawel also give quick guide to implement ZFS at FreeBSD
How about jails? Just check this blog for more ilustrative example
Soon … coming soon I’ll try ZFS, started from updating SRC
P.S : DragonFly will port ZFS too