Phornix.com just released some updated numbers from benchmarks they took using the recently released GA version of the native ZFS kernel module for Linux. They conducted a total of 10 tests using the ZFS kernel module, Ext4, Btrfs and XFS.
The tests were performed using Ubuntu 10.10 and kernel version 2.6.35 for the ZFS tests, kernel version 2.6.37 was used when testing the other three filesystems.
It appears that these tests were all run using single disk setups, I think it would be really great if Phornix would also look into providing benchmarks on multi-disk setups such as ZFS mirrored disks vs hardware or software RAID1 on Linux. I would also like to see benchmarks comparing RAID5 on Linux vs RAIDZ on ZFS. I think these kinds of tests might provide a more realistic comparison of real world enterprise level storage configurations.