The ZFS On Linux project is the native port of the file-system as a Linux kernel module along with related Solaris bits to make the port work in the Linux world. This isn't the ZFS FUSE implementation running in user-space. However, due to ZFS still being under the CDDL that's incompatible with the GPL and no re-licensing by Oracle, there still stands very little chance of seeing the ZFS file-system enter the mainline Linux kernel code-base anytime soon.
The ZFS On Linux work is lead by the Lawrence Livermore National Laboratory and other developers. The developers feel "ZoL" is now ready for wide-scale deployment after it's been in use by "real users" for the past two years. They noted this when announcing the ZFS On Linux 0.6.1 release this week.
ZFS On Linux 0.6.1 changes include Linux 3.9 kernel compatibility, a new snapdev property, improved slab object reclaim behavior, a disk cache flushing fix, hot spare functionality fix, updated DKMS and KMOD packaging, new man pages, and much more.
More details on ZFS On Linux 0.6.1 can be found via the Google Groups announcement.
New benchmarks of ZFS On Linux compared to other Linux file-systems will likely come soon. The last time at Phoronix we did extensive ZFS Linux benchmarks was last summer with ZFS On Linux With Ubuntu 12.04 LTS.