I wrote some blogging tools way back in Mathematica V 5 which I used for a while. But I haven't revisited the process since then. It's in a set of tools that I wrote for myself (and still use for the general organization of my work in Mathematica). I think a lot can be done to create a new approach if one wanted to--but getting things right is subtle to reproduce all that one can do in a notebook, so taking an approach (if one forgoes the HTMLSave route) where some rules are set that restrict what one can put into a notebook that will be exported is the best starting point, rather than trying to get all the bells and whistles working. Paul-Jean Letourneau's tools are a good start. Internally it seems that Wolfram Research apparently uses a complex workflow (perhaps a WRI employee can comment) to create their blog postings.

But here is what I did about 10 years ago:

The set of tools (I give it away for free these days if anyone's interested... no support though anymore):

http://scientificarts.com/worklife/

Documentation on the blogging functionality:

http://scientificarts.com/worklife/documentation/blogging.html

Some (old marketing) examples of blog postings:

http://scientificarts.com/worklife/wlfwblog/index.html

If I were to do this again I'd certainly take the route to implement it (at least as an option) some form of Markdown along with things like TeX/MathJax, etc...

P.S. All this stuff in this set of tools still works 10 years later with only minimal updates to the code. An amazing testament to the backward compatibility of the Wolfram Language, given that the codebase for this is about 50,000 lines... !

Hi Vitaly, all very convincing reasons and I will certainly also use the Wolfram community and cloud in the future for a wide and highly competent audience. Thanks for the good links.

Thanks a lot for the prompt answer Calle. I will try to install the "Classic Editor" plugin and use your package.

Your blog looks great, exactly what I was looking for!

I have made a package that can export notebooks to WordPress, which is also how the Wolfram Blog works. I have described my package here:

http://wolframlanguagereviews.org/2018/10/28/posting-notebooks-to-wordpress

You can see an example of an article here:

http://wolframlanguagereviews.org/2018/08/09/domain-decomposition-method-using-graph-coloring

You can get the package here:

https://github.com/cekdahl/wl-wordpress-xmlrpc-client

Unfortunately, it's not particularly easy to set up or use at the moment. WordPress 5 brought with it a regrettable change, the Gutenberg editor, which is incompatible with this approach because it doesn't let you store custom HTML. It will always try to change the HTML for you, even if you don't want it to. I solved this by installing a plugin which disabled the new editor and reverted to the one in WordPress 4, but even here there is the caveat that you must never use the WYSIWYG editor because if you do it will mess with the HTML.

To sum it up, I have written a solution that works well for me but it is not yet easy for others to use so you have to be prepared for some trouble if you decide to use it. So far, I know of one other person who has successfully installed it.