Last week a purple unicorn (a stuffed one, not a real one) generated some confusion at a border station in Turkey. According to this article, a family including their nine year old daughter, travelling across the Turkish border accidentally used the stuffed unicorn's toy passport instead of the daughter's real passport. The officer checked the passport, officially stamped it, and then let them through. At this point, the story deviates based on the source. Immigration said that the officer just wanted to be kind to the girl and forgot to stamp the real passport too. The family reports that there was no hesitation and that their daughter may have just have slipped through.
This story serves as a good reminder that security measures are only as good as their implementation. From crypto-graphical functions implemented with static initialization vectors, to passwords that are derived from public MAC addresses, to Web applications with poor session management that can be bypassed by calling the API directly. There are many examples throughout history of secure technology that actually had large, gaping security holes once they had been implemented. These examples do not even consider products that are implemented properly, but are not configured correctly or suitably integrated into the process so that the log files are never read.
If you are implementing security functions, ensure that you do it properly. Follow coding standards and play the attack scenario through. If you install security products, make sure that you configure them to your needs. Take note, if you do not pay attention to the details, you might be overrun by purple unicorns.