So will this bypass prism-like surveillance methods?
IMHO, the plus for this is that if more and more people move to encrypted communication across the board, it will a) increase the work load of the likes of the NSA and GCHQ, and b) send a message to government.
Nothing, of course, will work as well as people actually voting for real change. Of course the tragedy of that is that after the scary Bush years, the US people thought they were voting for changes, and all they got was more of the same. I despised Bush, but like we Brits used to say about Thatcher, at least we all knew where we stood. (Blair was our Obama, we thought we were voting for change.)
Sooner or later, we will realize we need to break away from our traditional parties, and vote for something very different, instead of voting int he same thing over and over again because we are too scared of fundamental change, and frankly risk.
For now, we are all too spaced out with our retail and media narcotics to notice or want to change.
"Mailpile will download your e-mail from a mail server much like Thunderbird or Mail.app and process it locally."
PRISM and other efforts at tracking associations operate at the server and header level, this is not a useful countermeasure. It may reduce the amount of mail you leave on the server -- but so would a reasonable mail reader configuration.
Obviously, the vast majority of emails would still be unencrypted, and this does nothing for metadata. But anything that makes encryption less cumbersome to use is a good thing in my book.
You can't encrypt the message headers, so the To/From addresses, subject line, sender's IP (usually), and timestamp will all be recoverable.