I just saw the following putback notice come over the wire:
Author: Adam Leventhal
Latest revision: 17811c723fb4f9fce50616cb740a92c8f6f97651
Total changesets: 1
6854612 triple-parity RAID-Z
This is pretty sweet, and with the introduction of 2TB+ drives, using multiple parity drives will become essential to ensuring that your data is safe when a drive failures occur.