I'm seeing rather odd behavior on a XServe running OS X Server 10.4.5. Files created with permissions of 777 are changed to 077 when modified by a user other then the original owner. Also, ownership changes from the original creator of the file to the person who just modified it. I have to assume this is not the usual behavior, right? Any help here would be greatly appreciated. Thanks,
This is almost certainly a result of application file saving behaviour. Many applications will rewrite the file when saving rather that just updating it. This is a safety technique designed to minimise the chances of data loss if an error occurs while saving.
If you want to verify this, please attach a trace of the behaviour. See http://wiki.samba.org/index.php/Capture_Packets for how to capture a trace.
Closing, sine this is almost certainly expected application behaviour.