Startup Phanfare, which stores a lot of user generated media, announced today that they are in the process of moving all of their backups of stored user data – 40 terabytes – to Amazon’s S3 storage service.

Amazon S3 has been on a bit of a roll lately, recently surpassing 5 billion stored objects and growing fast.

It’s also racking up a number of passionate users who swear by it for reliability and cost savings. Phanfare is just the most recent example, albeit a large one.

Phanfare stopped short of moving all data over to S3, though. For now they are just moving backups. They admit they’d save more money by moving the storage function entirely to Amazon, but note that:

After all, right now, Amazon does not provide a Service Level Agreement (SLA) or even a phone number to call if you are unhappy with the Amazon web service. I don’t expect that Amazon will ever lose our data of course, but we would like an SLA before we bet our customer’s data on that.

On the subject of Amazon, rumor has it that they’ll be adding to their storage and computing web services by year end – and adding a MySQL database web service to compliment the other two.