In mentioning the tests and benchmarks on Phoronix for the next month, a few readers emailed in to ask about any new ZFS file-system tests, since after all Btrfs and EXT4 in particular are frequently being tested on Phoronix. The last ZFS Linux benchmarks I have done are from last year. Since then, the various ZFS Linux implementations remain available but aren't advancing at a expedited rate nor is their adoption.
ZFS FUSE has been a long-standing option for ZFS file-system support under Linux, albeit it's based upon FUSE. This makes it easier for ZFS to be brought to new platforms and not having to worry about frequent changes within the Linux kernel to maintain the file-system support. ZFS-FUSE also bypasses the licensing issues with the CDDL, for which Oracle/Sun licenses the file-system, being incompatible with the GPL. However, using the File-System in User-Space can cause a performance penalty. FUSE file-systems are also widely criticized by kernel developers, such as with Linus Torvalds calling FUSE for toys and misguided people.
The latest ZFS-FUSE release is from early March of 2011 when it reached version 0.7.0 and tested against FUSE 2.8.0. There hasn't been anything too significant out of ZFS-FUSE in the past year.
A more proper Linux kernel port of ZFS is done at ZFSOnLinux.org by the Lawrence Livermore National Laboratory. Due to licensing issues, ZFS still doesn't stand a chance at this point of being merged, but LLNL is still at least working on this ZFS kernel port and making it easy to try out via modules in Ubuntu PPA, Debian, and RPM form.
The latest release on the LLNL ZFS Linux side is version 0.6.0-rc8 with SPL 0.6.0-rc8 and was released on the 26th of March of 2012. This port is of ZFS pool version 28, file-system version 5.
Similar to the LLNL work, in the past was the KQ Infotech ZFS Linux work, but that is basically dead these days.
For those looking to toy with the ZFS file-system but not wishing to run Solaris, at least the BSD port (namely with FreeBSD/PC-BSD and Debian GNU/kFreeBSD) of ZFS continues to be in fairly good shape and with install/root file-system support.