The title is is misleading to me as it sounds like its going to be a philisophical round-up of, “where we are at”, with responsive design. Its not.
It is about the most sane, understandable and easily implementable method for serving specific images for their relevant platforms I have seen.
To summarise: You wrap each <img /> with a <div>. For large screens you hide the image and serve a large versions as a background. For mobile/small screens you hide the large background image and show the small sized image.
This makes a lot of sense to me, there are some shortfalls to this method, discussed in the article, but he thought this up in the shower apparently! Checkout the article.