in reply to Secure Perl Coding Standards
Entire books have been written on the idea of secured programming which might help you formulate your standard. Secure Coding: Principles and Practices is one such book on the topic of writing secure code. Writing Secure Code, Second Edition is another, and some sample material from that is available at this MS Press page for the book (which even includes some Perl info in the examples). Security Forest has books on secure coding rated, including the two above.
Secure web programming is mentioned at http://advosys.ca/papers/web/61-web-security.html. You might not be doing web programming, but don't forget your application domain has its own security issues no matter the language. Make sure you have standards in place for the application domains, too.
Read up on vulnerabilities and consider how to avoid them. Knowing what you're securing against is one of the best ways to formulate how you're going to secure something.
Above all, remember that untested security is likely very little security at all. Most security errors slip through from a lack of black-box testing of the code at its boundaries. Write tests to check boundary conditions and even completely invalid inputs that are unlikely to occur. Any interface to the user is an interface to a fuzzing tool.