No and yes [Was: HTML-only calculator?]
@Glen 1: YAML is just a way of representing markup in a way that you don't have to worry about matching closing brackets/braces.
But you do have to worry about whitespace, right? That's progress all right.
[Aside: before anyone says editors support proper indentation so whitespace is easy - editors also highlight unmatched brackets/braces/parentheses.]
NB: this is not to knock YAML at all (see below). But relying on whitespace instead of visible grouping symbols is not a core advantage.
And now to the positive part. To this old-timer programs and data are one and the same, configuration is data and thus an integral part of the program, and just about any project will use a number of languages and tools, each used where it's best fit for the purpose. With this mindset I am perfectly willing to consider YAML and JSON and their ilk "programming languages" that are used for describing data in arguably better ways (for readability, serialization, portability, etc.) than what is available in "real" programming languages that are in turn much better suited for describing procedures and algorithms. It looks perfectly natural to me to describe data in JSON and algorithms in python. Or whatever.
YAML, JSON, python, C, bash, and F# are all tools of the trade, and if a SW engineer writes N lines of python and M>>N lines of YAML (feel free to count files rather than lines, or whatever measure you deem most appropriate) as a part of his project then he does more YAML than python, and that's perfectly fine with me.
A possibly enlightening example is Google's protobuf that is also a portable serializaton format, can easily be used for configuration, looks a bit similar to JSON (at a stretch), and is compiled into "real" data structures - classes with methods and everything else - in a multitude of programming languages that you can look at as (quite human-readable, albeit less so than the original protobuf) code in your favourite programming language. Once you look at how it works you may be more open to the idea that writing such stuff is programming.