I got Zevo CE the other day and have been putting it to work. At one point I wanted to dismount my sole zfs filesystem (/Volumes/big) and since I had Disk Utility up, I tried it from there. It eventually dismounted (I think I had to exit a shell first) but when I tried to mount it again I got the "you didn't put this away cleanly" popup, it wouldn't mount, and "zpool list" said I had no pools. Like the whole thing had vanished. A reboot brought it back, and a scrub finished with zero errors. Nothing I read so far said I shouldn't be able to do this.
Bit I won't do it again. Lion Server, 10.7.5. Only 4GB of memory, but over 1GB is free.