This is an excellent idea. “Are you sure” pop-ups are annoying. Building confirmation into the button itself if much cleaner and more efficient. I agree with Brett Andersen that the design of the button in the article isn’t terribly intuitive. I’m sure anyone could figure out how it works but it may not be immediately obvious to someone who’s never seen one before. Some instructions to guide users might be good until the idea catches on.
Another option is to make a button that has to be held down for a couple seconds with a “loading bar” type animation that moves across it. This might be more intuitive for a first time user because they would see the animation as soon as they clicked the button. Or maybe a button that has to clicked twice (although that’s hardly better than a pop-up window).
Anyway, great idea. Definitely something I will try to incorporate into my designs. Thanks for writing!