On my “way to the clouds” I find customers ask for EU or US regulation of cloud facilities and SaaS delivery standards. I searched the web for more information and I have found that NIST is the most trusted anf the on that is most close to be a “certified” for defining the standards in my opinion.
NIST states that cloud apps are “The capability provided to the consumer is to use the provider’s applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., web-based email). The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.” Check for more NIST definitions here.
Read more about cloud computing and SaaS on NIST site.