Jeremiah Foster has already posted that ZFS, the open-source 128-bit file system, is coming to Leopard. I just wanted to add that where ZFS totally rules is in handling multiple disks, creating virtual storage pools that span more than one physical device.
Other cool stuff includes “snapshots” that retain access to unchanged data for updated files and which create read-only restore points, “copy-on-write” that keeps the file system from overwriting live data, and dynamic striping, which boosts system throughput while distributing the write-load across storage devices. And that’s not even mentioning OS-integrated check summing for data integrity.
I’m not sure that ZFS will entirely replace HFS+ any time soon, but it’s nice to see that Apple is moving in the right direction. I haven’t had a huge amount of exposure to ZFS, so if any of you Sun Microsystems-type folk want to chime in, please let us know your thoughts about the file system.