ZFS boot support was just integrated (x86/x64 platform for now). It will be available in SXCE build 62.
Yes, we'll be able to boot directly from ZFS - that would definitely make life easier - no more hassle with separate partitions and their sizing, snapshots and clones for / and much easier live upgrade - those are just some examples. In b62 installer won't know about ZFS (yet) so some manual fiddling will be required to install system on ZFS.
Also in b62 gzip compression was integrated into ZFS (additional to ljzb) thanks to Adam Leventhal. It not only can save you lot of space transparently to application but in some workloads it can actually speed up disk access (if there's free CPU, disk IO is a bottleneck and data are good candidate for compression). We've been using zfs built-in compression (ljzb) for quite some time on LDAP servers - on disk database size reduced 2x and we've also gained some performance. It would be interesting to try ZFS/gzip.
Ditto block support for data blocks was integrated in b61. It means that we can set new property per fs basis (zfs set copies=N fs, N=1 by default) to instruct zfs to write N (1-3) copies of data regardless of a pool protection. Like with ditto blocks for meta data if your pool has more vdevs each copy will be on different disk.
ZFS support for iSCSI was integrated in b54. It greatly simplifies exposing ZVOLs via iSCSI in the same way sharenfs simplifies sharing file systems over nfs.
In case you haven't noticed 'zpool history' feature was integrated into b51. It stores zfs commands history in a pool itself so you can see what was happening.
Of course lots of bug and performance fixes were also integrated recently.