Pretty often I use one widget area placed in the footer of my theme, what displays its widgets as columns. As a theme developer I try to offer as much flexibility as possible. So if the theme user wants a specific amount of columns in the footer, than 1, 2, 3 or 4.. columns. It shouldn't be any problem, they all will fit perfectly (as long as css supports it).
Unfortunately I couldn't find a way to render my widgets in a similair way as posts are rendered. I want an array of widgets of a specific area, so I can count them and calculate what column class should be used on the container element of the widget.