From Peter Krautzberger of The MathJax Team:
We are entering beta testing for MathJax v2.3 today. This release focused on new webfonts options and improvements. It also includes improved localization features and improvements to our Native MathML output (to work around shortcomings in Firefox and Safari).
A copy of the beta release is available via our CDN at http://beta.mathjax.org/mathjax/latest/MathJax.js and also via a stable https address. Please note that the beta now has its own subdomain. You can also download the beta as a zip file at https://github.com/mathjax/MathJax/archive/v2.3-beta.zip.
If you are able to test the release, we would very much appreciate your feedback. I’ve copied the upcoming announcement with more information below.