I hope this shames Dropbox into implementing proper client side encryption.

I like many others have become dependent on Dropbox for my work because it is so darn convenient but I know in the back of my mind that it poses a security risk. I would feel much more comfortable if everything was encrypted on my PC (and under my control) before it was transmitted.

You say that the information didn't come out to every one but nevertheless there was plenty written over the last few weeks saying that Facebook was overvalued. There was no shortage of warning signs so it is hard to feel sympathy for those who lost money on this. Caveat Emptor and all that.

This seems relevant to me even if it dates from the dawn of computer time:
http://www.adequacy.org/stories/2001.12.2.42056.2147.html

I am surprised it hasn't been linked to yet.

I am pretty sure you mean Jonathan Swift's modest proposal. I know this only because I work right beside the cathedral where he was Dean.

Pretty cool idea to put passengers to sleep by the way. Apart from security concerns it would finally allow me to get some sleep on long haul flights.

to see if they can they release version 1.0 of ReactOS before the X86 architecture becomes obsolete.

Just to clarify the situation I guess we have to assume that the encrypted files are are in the cloud or already in the hands of the authorities so you cannot just destroy them.

Vegemeisters suggestion of a key-file on a Flash disk seems like the best idea so far but flash disks are pretty robust little devices how could you be sure of destroying it in time? You are hardly likely to carry a hammer or other heavy tool around with you everywhere and crushing it underfoot probably won't do enough damage. I guess you could have the keyfile on a phone along with an app that instantly garbles it beyond use but I amn't knowledgeable enough about such things to know how easy it is to permanently delete info on a phone.

If all else fails we could go back to the edible paper approach with a QR code password on it.

In the olden days folks had to eat their notebook pages or hastily burn them as the secret police were knocking on the door. Nowadays that information is likely to be stored in encrypted files and event the best passwords are susceptible to the judicious application of baseball bats. Is it possible to come up with a genuinely destructible password that can be quickly and discretely destroyed forever. My best guess is some kind of keyfile but how could you be sure to delete it in a manner that couldn't be reconstructed?

As long as you run dropbox on at least one desktop computer you have a local copy of your files. If you use more than one computer chances are you have multiple copies of those files. Of course you lose the ability to share those files when dropbox shuts down but at least you have the files in an easy to find place which should make it easier to move them to another cloud service. This seems like a fairly robust model to me.