[buugs]

Here is something 80 px wide http://www.novavision.com/clinic_images/Neurol%20Inst%20Colu...

to give you an idea of what kind of value can be added

Sure adding another column could be useful but as you can see by the authors tone he is talking about flow and divisions of columns and how those go well together and in all reality it sure doesn't make a hell of a difference even if you shrink something to add an extra column. After a while you get cluttered and usability/simplicity goes out the window.