Interesting Information has a nasty habit of leaking - particularly when information security is not being managed effectively. If you need ammunition to help convince those around you that security should be taken seriously then a useful aid is referring to sites such as http://www.internalmemos.com - the site contains many examples of information that's made it into the public domain against the wishes of the authors.

Effective information security requires a clearly defined policy that has consequences for those who fail to comply. The policy should be frequently reviewed by both stakeholders AND those it applies to.