It's a great story, but not a very repeatable one.
1) Step 1 - Build an enormous and rabidly loyal audience with a great blog (SvN) and a great framework (RoR). JoelonSoftware proved that you can do this without the framework. :-)
2) Release products that serves the core of that audience. Watch in amazement as profits pour in. Customer acquisition costs are near zero. No marketing required other than public speaking engagements (which often net a speaking fee) and the occasional blog post.
No doubt that these guys are really talented... But I don't think they owe their success to working less or giving their customers less. They owe it to an evangelical following and (to a much lesser degree) building an app that does a solid job of serving that audience.
I don't look to superstars or billionaires to find the secrets to success, usually their rise to stardom is very atypical and contains a good deal of luck (along with a lot of concrete factors like determination, skills and timing).
I just tend to get annoyed with the self-righteous tone of many of their articles, which is then amplified by the blogosphere (probably more the source of my annoyance than anything 37 posts themselves).
I apologize for the troll like post, now back to the NBA finals (go Celtics!)
Until people realize that working a lot of overtime tends to generate a lot of technical debt, they'll keep doing it. And even though a 4-day week might be a bit short, you have to admit that it's working.
Attempting to build a business in the same manner is a false panacea; almost everyone else has some form of constraint that directs their decisions.
Some people need to work more than 4 days per week, actually need to hire more people and actually need to add features to their software (and can't say "no" to everything)
We don't all have cult like religious followers. It's like using Apple as a guide for starting a PC business. Not exactly a formula you can apply to everything.