One thing that isn't immediately clear to me is if there is are provisions for "dynamic" allocation of storage providers. That is to say, instead of selecting one host to store the encrypted application data, could some sort of routing/load-balancing layer be used to allow the application to automatically select and use a provider (and recover when a provider disappears unexpectedly)?
From a purely technical standpoint I believe the answer is "Yes". Whether or not it makes sense from a performance and cost standpoint is another matter.
I find the idea really intriguing though. We already have a general strategy of trying to spread our infrastructure between different providers even if it's just as simple as pushing backups of our Rackspace hosts to S3.
