I'm hoping web crypto will solve this, but only if the e-mail and storage service providers offer the option in an intuitive way, and I don't think the big ones like Google and Microsoft will want to do that unless we all demand it. It's also not going to be a finished draft until 2014, so we have to wait a little more.
Web crypto will never solve this, especially not when provided by a big company like Google/MSFT. They'll always have provisions to make the unencrypted version available to authorities. You can only trust client side encryption.
Yes, that's what I meant. Implement web crypto and allow the user to use his own encryption key. So nobody but you and the recipient can access it (unless they can crack it, of course).
http://www.w3.org/2012/webcrypto