Arguably, Salesforce.com brought the software-as-a-service (SaaS) concept mainstream. Today, if software isn't available as a service, it's considered old school. But software -- as a service or not -- is just a container. What makes software valuable has always been what it does to data. Now, in the same spirit of service-oriented architectures and SaaS, a new concept is emerging, Data-as-a-Service (DaaS).