Following disappointment at WWDC earlier in the Month, Apple appears to have taken somewhat of a U-turn.

Apple seeds disk image allowing developers full read/write access to ZFS in LeopardApple seeds disk image allowing developers full read/write access to ZFS in Leopard

Just before WWDC Sun Microsystems CEO, Jonathan Schwartz touted that ZFS would become a usable file system in Mac OS X and that Apple would announce it at WWDC. This never happened but Apple senior director of Mac OS X Product Marketing, Brian Croll confirmed that ZFS would be present but read-only.

Now Apple has published a disk image on its ADC site allowing developers to use full read/write capabilities of ZFS.

In a PDF released with the seed Apple writes:

ZFS is a new filesystem from Sun Microsystems which has been ported by Apple to Mac OS X. The initial (10.5.0) release of Leopard will restrict ZFS to read-only, so no ZFS pools or filesystems can be modified or created. This Developer Preview will enable full read/write capability, which includes the creation/destruction of ZFS pools and filesystems.