I want to back up sensitive personal data to S3 via an rsync-style interface. I'm currently using s3cmd - a great tool - but it doesn't yet support encrypted syncs. This means that while my data is encrypted (via SSL) during transfer, it's stored on their end unencrypted.
I want to know if this is a big deal.
The S3 FAQ says "Amazon S3 uses proven cryptographic methods to authenticate users... If you would like extra security, there is no restriction on encrypting your data before storing it in Amazon S3."
Why would I like extra security? Is there some way my buckets could be opened to prying eyes without my knowing? Or are they just trying to save you when you accidentally change your ACLs and make your buckets world-readable?