I've been following snapraid fit awhile and been hugely impressed with Andrea. He's managed some novel work to enable far higher raid levels that not only works but is pretty damned optimized.
I had no idea he was interested in mainlining this work, however.
Snapraid is a great alternative to zfs for people with media libraries. In fact it is better for media libraries since it has it doesn't rewrite all disks to run in order to access data and you basically are never under risk of losing the entire array.