phoenix said:ZFSv13 is in FreeBSD 7.2 and 8.0.
ZFSv14 is in FreeBSD 7.3 and 8.1.
Patches for ZFSv15 and ZFSv16 are available for testing with 8.1.
Work is ongoing to get ZFSv22+ into HEAD.
ZFSv15 has been committed to HEAD and will be MFC'd to 8-STABLE in two months.