Security through obscurity can be a good thing – if it is part of a multi-layered approach to security.
Consider the following entries in my apache error log:
[Tue Jul 06 08:52:44 2010] [error] [client 208.71.173.74] File does not exist: /path/to/public_html/phpmyadmin [Tue Jul 06 08:52:45 2010] [error] [client 208.71.173.74] File does not exist: /path/to/public_html/pma [Tue Jul 06 08:52:45 2010] [error] [client 208.71.173.74] File does not exist: /path/to/public_html/admin [Tue Jul 06 08:52:45 2010] [error] [client 208.71.173.74] File does not exist: /path/to/public_html/dbadmin [Tue Jul 06 08:52:45 2010] [error] [client 208.71.173.74] File does not exist: /path/to/public_html/mysql [Tue Jul 06 08:52:49 2010] [error] [client 208.71.173.74] File does not exist: /path/to/public_html/myadmin
TIP: if you have phpMyAdmin installed on your server, for goodness sake don’t give it an obvious name!