The following question is one that I have wondered for some time, even as it applies to not only Wolfram Language but others What programming language would be worthy of learning that is both consistent with our belief of universal systems found in nature, AND capable of building a more advanced CMS platform?. After trying to learn about what has been built using the wolfram language I had hoped it was capable, and in fact had already been used, to build a type of platform, for instance one even as simple as this community forum, but unfortunately I cannot find this seemingly simple answer.
This maybe a ridicules question but as someone that is not a programmer by training but rather have had to rely upon, at least up to this point, others peoples creations and uses of a their chosen programming language, using such languages as PHP, .net, and many others to build their attempts at a myriad of platforms such as SharePoint, Drupal, Even Facebook and Google Plus but myself and a few others are getting so frustrated with these and others and are looking to hire someone to build our own but the only language that seems of interest to us is the Wolfram Language. So my question is, before trying to do something that would be simply impossible or even impracticable, (and I hope the wolfram community does not mind this question being asked here in this community forum) AS far as programming languages go, How far is the wolfram language able to take us? Has it been used ever to build a CMS or is it just for Computational output, could it be used to build an entirely new breed of content management or is the Wolfram Langue not able to be used for such an endeavor as this?
Please forgive the lack of understanding and abilities of this seemingly powerful and ever evolving programming language.
I think that, broadly, the answer to your question it "quite far"... subject to some caveats. Some are economic, and others are technical.
The content of http://mathworld.wolfram.com is generated from Mathematica.
Textbooks are written and deployed using CDF
I have written, for a client, a recommendation engine running on the Amazon cloud which provides updates to recommendations on a start-up company's web site.
Wolfram Solutions (http://www.wolframsolutions.com) creates a very wide variety of Mathematica-based applications for consulting clients.
And the list goes on. So, my general response (which I give to my consulting clients) is that most things are possible and, depending on their specific needs, it's worth exploring the model of computation and deployment. And it is always worth pointing out that the the development loop (and the ability to implement very advanced algorithms, as well as explore the space of idea possibilities) is very fast compared to pretty much any other technology (http://www.wolfram.com/solutions/industry/operations-research/research-and-development-information-kit/).
On the economic side of things it is of course important to make the direct comparison of long-term "steady-state" deployment costs. The issues are more complicated that one might think on first glance, and it's therefore wise not to dismiss Wolfram technologies too soon based on economics: the comparison of paid-for licensed integrated powerful technology (Wolfram) to an open source amalgam of technologies (Python, Drupal, PHP, etc...).
So, that's a summary of some aspects of the dialog surrounding your question.