nidump on MacOS X before 10.3 allows local users to read the encrypted passwords from the password file by specifying passwd as a command line argument.
http://www.securemac.com/macosxnidump.php
http://securitytracker.com/id?1001946
http://marc.info/?l=bugtraq&m=99953038722104&w=2
http://lists.insecure.org/lists/bugtraq/2002/Sep/0128.html
http://lists.apple.com/mhonarc/security-announce/msg00038.html