We've recently started to convert our users over to NFS home
directories, which had previously been served with AFP. The host is
running OS X Server 10.4.8, with all Mac clients. The NFS settings
are pretty normal (exports to class-c sized subnet, map root to
nobody, not read only).
There appears to be a problem when users try to run applications out
of their home directory that need to access the login Keychain. For
example, if I were to copy Workgroup Manager to my desktop and try to
use that copy to connect to a server (using credentials stored in the
keychain), it would bring up a "Confirm Access to Keychain" dialog
with some bogus information: "UNKNOWN wants permission to use the
"Workgroup Manager: dspx://server.company.com" item in your
keychain." Selecting "Always Allow" will not grant access to the
keychain.
This problem seems to affect any application whose binary is on the
NFS share that reads from the keychain. Oddly enough, apps don't seem
to have trouble creating new keychain items. Disk images and local
filesystems aren't affected.