The approach described in this blog post builds a JavaScript app from the get-go, and uses a server-side technique to extract standalone HTML from the JavaScript application.
The net effect is the same (you get HTML on the client before you executed the JavaScript), but the developer paradigm is sharply different.
Typical progressive enhancement techniques require you to carefully construct a version of your application that works without JavaScript, and then find ways to shim in and bring the page alive. The approach I'm working on provides the HTML as a by-product of running the application normally.
Additionally, progressive enhancement techniques almost always involve server-side rendering, which means you lose the benefits of client-side routing I describe in the post.
The goals of progressive enhancement are wonderful. My complaint has always been that previous techniques hamper developer productivity far too much to be realistic. With FastBoot, I'm hoping we can offer the benefits with far fewer costs.