ZFS
Just looked back over some words I wrote in 2007 (emphasis added):
Apple currently (with Mac OS X Tiger) provides a journaled filesystem in the form of HFS+, but I have had multiple catastrophic failures of HFS+ volumes, both when used independently and when configured as a software RAID, so I cannot recommend HFS+ for use with any data that you aren’t prepared to throw away. HFS+ is effectively a "throwaway filesystem".
In Leopard Apple will support ZFS which is a revolutionary filesystem developed by Sun. It supports journaling, advanced RAID, and unparalleled data integrity verification and self-repair. Apple has publicly stated that ZFS support will be read-only at first, but we can definitely hope for and look forward to read/write access and bootability from ZFS in the future.
Still sad about this, and still mostly unimpressed with HFS+, although Apple has made some nice improvements in the form of Core Storage and a much-improved, whole-disk File Vault implementation.
Will we ever see ZFS or anything comparable on OS X? It’s pretty clearly the world’s best desktop operating system, but in filesystems it feels like it lags behind.