I could care less if this is open source, if I'm going to offload my data to a 3rd party, open source or not and I'm worried about privacy I'm going to encrypt it. I honestly could care less what happens on the back-end, just commit to a data loss and reliability SLA and I'm happy.
If you can support my use case, or have reliable performance near 370k requests/sec (http://aws.typepad.com/aws/2011/10/amazon-s3-566-billion-obj...) and be cheaper than S3 then we'll talk.