The Front End
The Automattic team (the company behind WordPress) has chosen React and Flux for their main front end library. This is interesting because it will place React as one of the most used frameworks out there. With Facebook still backing this framework, we will see more and more of it (although it was pretty much already the flavor of the month.
The Fun Parts
As I went through the WordPress Calypso Github repository (yup, it's open source), what I found to be the most interesting part is their whole build process. They are now using a full Node process to manage all their packages. Webpack, Babel, Jade and Uglify and just some of the 100+ packages that they are using.
Will I use WP from now on ?
Well, probably not right now. This is for their admin interface. It seems very interesting and it might make it easier to create an interface that is easy to use for the WP administrators. Thing is, I kinda like this interface that I built myself for this site :).