c63a6c4 created the issue
Using Leopard (9A527) and CyberDuck 2.8b1 (3212)/3212, and SubEthaEdit as an external editor, I notice that when editing a file and saving back, the file is not re-uploaded.
This is logged to the console:
9/10/07 12:58:29 PM Cyberduck[1178] handleModifiedFileEvent: Got ODB editor event for unknown file.
9/10/07 12:58:30 PM Cyberduck[1178] handleClosedFileEvent: Got ODB editor event for unknown file.