Data is so persistent - and pervasive - that it's hard to ensure a secret is kept, once it's online.
By that, I mean that traces always remain, somewhere. For example, if you send an email to someone, you may live to regret it. But you can't expunge it. There's the copy on your computer, one on the recipient's computer, and one on each of the email servers of the ISPs that service each end. And despite what ISPs say about the difficulty of retrieving an accidentally-deleted email, can you be sure that your message is not archived somewhere? - indefinitely?
Enter Vapourware with a whole new meaning.
This report discusses a new product called VaporStream. One person types in a message to the application, it is stored temporarily on a server somewhere - securely - where someone else can click to read it once - but not copy it. After reading, the message is deleted from the server permanently.
Of course, this is not for everyone. As the article points out, much of a business' electronic activities have a legislative requirement to be stored. But there is also an amount of message transactions that are actually a pain to retain, and difficult to completely remove.
And, of course, people have secrets, that they don't want persisting in stored messages.
However, I can see a simple flaw in this. You cannot guarantee the recipient hasn't done this: capture a screenshot of the message, via the ctl-print scrn buttons.
But if you trust the recipient, this may be your best punt at preventing your secret pervading.