It has been a while since last benchmarking the ZFS file-system under Linux, but here's some benchmarks of the well-known Solaris file-system on Ubuntu 12.04 LTS and compared to EXT4 and Btrfs when using both a hard drive and solid-state drive.
Last year I benchmarked the official KQ Infotech ZFS implementation for Linux but that port is no longer active. There is also ZFS-FUSE, but that has not been too performance-friendly and FUSE remains widely criticized. Lastly, there is the fledging LLNL ZFS port for Linux. The "ZFS On Linux" port from Lawrence Livermore National Laboratory (LLNL) is what is being benchmarked here. It is basically the only serious ZFS implementation for Linux unless you count FUSE.
ZFS file-system support is not in the mainline Linux kernel since its license (CDDL) remains incompatible with the GPL code-base. Lawrence Livermore National Laboratory meanwhile makes all of their source-code publicly available so the user is free to build the kernel modules themselves. There is also some support for easily generating RPM and Debian packages for Linux ZFS as well as an Ubuntu PPA. The most recent release of ZFS on Linux is 0.6.0-rc9, which was released on 14 June and is what is being tested today. zfs-0.6.0-rc9 implements Zpool version 28 and FS version 5. There is also a matching SPL (Solaris Porting Layer) release.
At ZFSOnLinux.org is much more information on the supported features, ZFS examples, and other items.
On an SSD and HDD the ZFS 0.6.0-rc9 performance was compared to EXT4 and Btrfs from Ubuntu 12.04 LTS. All file-systems were tested with their stock mount options. The system was built around an Intel Core i7 3770K "Ivy Bridge" processor. The SSD used for benchmarking was an OCZ Solid 2 and the rotating drive was a Seagate Barracuda 7200.10 SATA 2.0 HDD (ST3320620AS)