Cloud vendors including IBM, Microsoft and Rackspace got together last year to create a single API that would work with cloud services from multiple providers. The result was the Simple Cloud API, a common API that allows developers to write portable code that can interoperate with multiple cloud vendors. IBM Cloud Computing Evangelist Doug Tidwell provides a high-level overview of the API and its goals in the simply titled IBM developerWorks article, The Simple Cloud API.
He summarizes what motivated the Simple Cloud API vendors to collaborate like this:
Cloud computing can have significant economic benefits, but if using the cloud puts you at the mercy of a vendor’s pricing strategy, that’s a major concern. … It’s vital that your applications be able to work with as many providers and services as possible.
Ostensibly, the Simple Cloud API will allow you to use services specific to a particular vendor as well if your setup calls for that.