Just saw this pass by on nfsv4.org mailing list from Rick... excellent news!

If anyone is interested in trying an NFS Version 4 client (including Kerberos
support) on xnu-792.6.70 (Mac OSX 10.4.6 on PPC or Darwin8.0.1 on x86), you can
download the patch from (currently Beta test, I'd say):
ftp.cis.uoguelph.ca:/pub/nfsv4/darwin-port/xnu-client.tar.gz

There is also a "Readme" file and a primitive web page at:
http://www.cis.uoguelph.ca/~nfsv4

If you are interested in seeing further announcements related to this,
please join openbsd-nfsv4@sfobug.org. I'll try and refrain from spamming these
lists with announcements most of you aren't interested in.

Just in case you are interested in it, rick
ps: If you have already downloaded the patch, you should do so again,
    since I just updated it a few minutes ago.

Perhaps soon my laptop will have NFSv4 and ZFS....