And just as a heads-up to those who haven't watched, implementation details and code samples are coming tomorrow.

But basically the tl;dw seems to be that you can write JavaScript React code that runs efficiently on mobile and renders native primitive components instead of dom primitives (<View> instead of <div>).

It also introduces the idea of "Learn once, write everywhere" instead of "Write once, run everywhere", which I think is a great idea.

Here is the philosophy behind React Native: https://www.youtube.com/watch?v=KVZ-P-ZI6W4#t=1725

"Learn once, write anywhere."