A wonderful overview of why progressive enhancement and inclusive design go hand-in-hand, and why both are still necessary and deeply useful techniques for modern web development. I particularly liked Matthias' breakdown of why design tools should provide the ability to build/prototype designs progressively as well, so that designers can more easily understand how their work will actually end up deployed:

Because in order to practice progressive enhancement well, every member of the team has to be able to make well-informed decisions. If a designer never sees a design in its most basic form, how can she possibly improve this state of the system?