Just a quick note to help those that are upgrading to Mavericks and use NFS automounts.
By default, Mavericks will use NFS4 which uses a different security model so you may end up with what appears to be a regular mount, but it’s pretty much empty. Don’t worry the data hasn’t gone away or been deleted. It’s just that the user mapping doesn’t just cross check the local and remote UID of the user the same way, especially if you’re using PAM to grab UIDs from an LDAP directory.
I haven’t yet pieced together the best method to move to using NFS4 natively with my Solaris and OmnisOS boxes, but in the meantime, you just need to force the connection in NFS3. If you’re using automounts for user home directories, then add ver=3 to the automount entry and all will go back to normal.
Connecting via Command-K in the Finder with an NFS URL doesn’t seem to be affected at the moment.