It seems that apple is providing full ZFS support voor the developers.
When you check the man pages for ZFS in 9A466 you find this :
A full ZFS implementation that allows all subcommands and is read/write is available for download at http://developer.apple.com/.
To determine which version of ZFS is loaded(readonly or writable):
# kextstat | grep zfs
com.apple.filesystems.zfs.readonly is the readonly kext version. com.apple.filesystems.zfs is the writable kext version.
So now my question, who of the developers can get dat package so we can have write support in Leopard 9a466 ?