That's correct.
To be exact, FreeNAS partitions on 4K blocks when created via the GUI. In FreeBSD, Solaris, Linux etc... you simply create them either by;
1) Creating partitions on 4K blocks then use them in ZFS
2) Creating your zpool with the -o ashift=12 which creates this layout on each drive;
Number Start End Size File system Name Flags
1 1049kB 3001GB 3001GB zfs
9 3001GB 3001GB 8389kB
* Linux used in the example.
Prior to this, the drives were raw, partition-less if you will.
Otherwise if you simply create your zpools on raw drives, you will most likely get an ashift of 9. Unsure how SAS or FC drives are handled, or even other SATA drives for that matter. But mine being Seagate Constellation ES.2, will be seen as 512byte sector capable even though 4K is supported.
I found this very interesting and educational. I'm testing various distros that support ZFS. So far, even thought I prefer CLI, FreeNAS seems the win. Still finalizing my testing however.
I should have considered FreeNAS last year during an important storage transition project but that ship has sailed, for now anyways. This one I'm on now is the flag ship.
I still can't get over the thoroughness and flow of the documentation, simply amazing. I even have it on my Kindle :)
How do these guys make money, there main distro is free. And then they hired some high end guy from Apple with deep FreeBSD roots, that ain't cheap.