Is there any difference in revenue recognition standards between IaaS, SaaS or PaaS service models?

Anon,

No, but....

I think of these three as levels of specificity in the software stack. In all of them, the goal is to productize the interaction between the customer and the software to the extent that the base offering is a general case that doesn't require customization. In that sense, a pure XaaS model is what it is, be it CPU time, OS time, or Software time.

The but comes in when there are devils in the details, such as training etc that get bundled in, migrations or customizations that are required for the basic functionality, and the list goes on. Some of the new complexity, such as estimated selling prices of theoretically separable elements, also impact all of them. I don't think any of these are more or less prone to these issues. Even if they are, you're still talking about fundamentally identical concepts.

KP