Can we answer here? That's what I'm going to do because it seems the better venue and I don't have to type into a small box.
This raises a number of questions. What does "freely available" mean? Can we expect a major change in the business model? And what does Stephen mean by " the programming language of Mathematica ". Is it everything one types in a notebook? Or just things that get sent to the kernel? How about things that get sent to the front end? How about Text cells and Section headers?
The way I feel about it is: "We don't need no stinking programming language!" Many of the employees at WRI need a programming language but why do the users need one?
Instead of thinking of writing a computer program, why can't one think of writing function definitions, equations, specifications (for a graphic or table say, or for initial data), axioms (as Rules say) and other literate forms of expression? I like to think of Mathematica as a piece of paper on which we develop, write, and communicate ideas with a significant mathematical or computational content.
So how about a name like MagicPaper because the piece of paper has rather magical qualities, with its computational power, memory and access to a wide spectrum of information? Or maybe CPR for Computational Paper with Resources. It really does get to the heart of the matter. Maybe static "Paper" is not quite right but Windows might annoy the Mac people and Screens isn't too great. Anyway, paper was used to doodle, try out ideas, calculate and do symbolic math, and communicate ideas and that's what we want to catch.
I see people who write in "Mathematica" as ranging from those simply using it as a graphical calculator, to those writing extensive scholarly works (which I call Actomes for Active Tomes) that consist of books in the form of a collection of notebooks, a number of packages with full documentation (through Workbench unless WRI comes up with something better). These can be wonderful things because they can act as a vehicle for exchanging ideas and further development between authors and readers, or among groups of readers. The other users are readers of such productions.
It doesn't seem quite right to try to isolate the "programming language" part of this - or even think in the paradigm of programming.