ZFS on OS X (10.5 Leopard)

ZFS has a (mostly) working port for OS X. There are some minor quirks associated with using it, and similar to the current Solaris releases it cannot be used as the root filesystem (yes, OpenSolaris can currently do this).

The page for this project is: http://zfs.macosforge.org/trac/wiki/

Some of the pitfalls I've encountered include (these are known issues):

• Finder, and some relatively expanded directory names associate the name of certain folders at mountpoints with the root name of the pool, instead of the name of the actual folder at that mountpoint. Meaning, if your pool is named tank, and you mounted tank/Music to /Users/asherwin/Music, some programs such as iTunes that automatically attempt to use ~/Music will resolve the directory to ~/tank, or /Users/asherwin/tank. There is no workaround for this, and it means you can't do certain things (such as use a ZFS filesystem as a home dir... I've tried, and it just poses too many problems with this current limitation).
  
• Issuing a scrub command results in a kernel panic.
• The special .zfs/snapshot directory functionality is not yet ported, but snapshots still work (you can mount a snapshot temporarily to utilize it).
  

If you like to tinker, and can live with some minor inconveniences, this is a great technology to play with. I've been using it successfully for over a month with no problems, besides the known issues.