During our recent meetings, there were a fair number of questions and discussions about the economics of public cloud storage providers, such as Amazon's S3 service.
This YCombinator discussion has lots of good information about pricing, usage and experiences of some of S3's supporters and detractors. It's well worth reading.
Interestingly, thanks to a new S3 user space file-system FUSE module, Bycast has pretty much everything we need to provide a S3 tier of storage to our StorageGRID customers. Of course, such a capability would need to be productized, which would allow an administrator to have a place to configure the tier and securely enter and store their S3 credentials through our administrative interface, but thanks to the filesystem virtualizing the S3 API, all the hard work is already done.