Wow that's one bizaare claim in the article "Emails, Facebook messages, and Google Docs can all be set to disappear into thin air". There is not the slightest possibility that Facebook or Google are going to enable this as a feature. Email is conceivable, but only if the recipient has an email client that is enabled for this kind of cryptography. Typically poor BBC technology journalism.
People just don't grok cryptography. Once you decrypt the thing (to READ it) it can be copied, decrypted. Game over.