> Google can't stop the NSA from slurping up traffic. But they can prevent that data from being massively decrypted via a single key.

I don't want to sound snarky, but, so what? If you want privacy you still have to encrypt data end-to-end, not end-to-[google|microsoft|yahoo|facebook]-to-end.

And, anyway, [google|microsoft|yahoo|facebook] should not know about your stuff just like the nsa or anyone else who is not the intended recipient.