Apple Looking To Port ZFS for Mac OS X?
According to an OpenSolaris mailing list, the ZFS team at Sun has been contacted by Apple's Filesystem Development Manager to discuss porting ZFS to Mac OS X.
ZFS is a relatively new open-source file system backed by Sun. As such, it is included in recent versions of Solaris for SPARC and x86 architectures. A comparison of HFS+ (what Mac OS X currently uses as its default file system) and other file systems including ZFS can be found on this wikipedia page.