According to this article on NewScientist
The four-day week could boost employment, save energy and make us happier.
If one really think about this, it makes a lot of sense. In the state of Utah, they actually experimented with it and energy fell by 13% and employees were much happier, even though they worked the same amount of hours in the week.
Now I just wonder if my company, IBM will allow me to do this. Then again we can in any case work from home if and when it suits us. It is a known fact that around the world, IBM only has office space and desks for about 50% of their staff. The rest, either work on customer sites or at home.