Looks like some people have started another effort to bring ZFS to the Mac (https://github.com/zfs-osx/ and http://MacZFS.org/) and development seems to be active right now. They are starting off with the sources from the LinuxZFS version, which (due to the SPL layer) might be easier to keep up with current ZFS implementations.
I myself like the build quality of ZEVO's implementation, but we haven't seen updates for 6 months now - which worries me a bit.
But what worries me the most is the ongoing problems I have with using ZFS on the Mac. Apple is not supporting 3rd party Filesystems actively. This becomes very visible when you try to use TimeMachine on a non HFS+ formatted volume or when you have your home directory on ZFS - which I do. Ever wondered if the next minor System update (10.8.3) breaks ZEVO ?
I do have my HomeDirectory on ZFS for over a year now and it's not fun. I only do it as I want a few of ZFSs features, but boy are Applications picky about their filesystem. TimeMachine, Versions, iCloud, FinalCut Pro - all programs that do not work on ZFS without hiccups.
If things go wrong, Apple could drop support for 3rd party filesystems alltogher in their next OS release.
I wonder what ZEVOs and ZFSs future on the Mac is. As for the Mac, there is probably nobody here who knows.
Patrick aka Jolly