nfs and shifting permissions

[Tony Laszlo <laszlo@example.com>]

Today's strangeness.

After ssh'ing into net.issho.org and becoming root,
I do this:

chown -R user.user /mnt/directory/otherdirectory/

As a result, all the files in the directory
become user.user.

_BUT_ when I ls -l /mnt/directory/
from asong2.issho.org, a machine
that has been capable of copying
to and from /mnt/directory/ because
it is connected via nfs, it shows
the files as 500.500 (!).

(the following
is from asong2's /etc/fstab)

net:/mnt/store          /mnt/nfs                nfs
rsize=8192,wsize=8192,hard,intr  0  0

Then, when I chown laszlo.laszlo these
files from asong2.issho.net , they
look alright from asong2 but become
505.505 as far as net.issho.org is
concerned (!!).

What is going on?!