I've been thinking a lot about email security and encryption in the past year. Especially since everything you send on, for example, Gmail is stored on their servers forever, even if you "delete" it, and even if you're super-paranoid and use your own mail servers, you'll be mailing other Gmail accounts that record your activity anyway. 10 years from now the government could mine your past communications in ways never before imagined in the era of paper mail and paper shredders. Things you said a decade or even two earlier that were innocuous at the time could be brought as evidence against you.

Because of the nature of easily-copiable bits, the only real way to be secure in communications is encryption with something like GPG. But public/private keys are a completely unfathomable idea to regular people. Hell, they're even confusing to techies. Even if the concepts are understood, implementing and using them is cumbersome and error-prone to say the least.

That's why I think the most important thing to be working on, from a social-importance perspective, is a way to make GPG-style encryption friendly, usable, and easily-grokked. The problem of good-enough encryption has been mostly solved, I think--we just have to get people to use it!