EmptyCrate Software. Travel. Stuff.

What you're describing isn't exactly natural language processing. Rather, it's a domain specific language that has a very English-like syntax.

Some good references for DSLs:
http://martinfowler.com/dslwip/
http://www.pragprog.com/titles/tpantlr/the-definitive-antlr-reference

Or, if you prefer video:
http://msdn.microsoft.com/en-us/oslo/videos.aspx#dsl

The topic has been hot for a few years now, with the steady hope that more and more programming can be spread into stratas:

[DSL users] ~large group
[core programmers] ~tiny core

In the same way that Lua or LISP are used as a way to drive the core engine to do things, DSLs give the programmer a way to open up the core technology to experienced users who are otherwise laymen programmers (though not always, DSLs can also be used to quickly write new code).

Back to your example, I think Inform's approach is pretty slick, though I haven't studied it very deeply. At first glance it sounds like a great place to jump off creating DSLs for "normal people".