Rule of Thirds?

I read a short article on about.com about the Rule of Thirds:
http://graphicssoft.about.com/library/glossary/bldefruleofthirds.htm

This article surprised me somewhat as I have never heard about such 
rule. I do however know of the Golden Section.


The Golden Section positions the lines approximately 38% from the edges 
of the picture, whereas the Rule of Thirds positions the lines 
approximately 33% from the edges. If I overlay the two types of guides 
on an image, I find that the suggestions for composition are rather 
different.

I know that both the Rule of Thirds and the Golden Section are 
suggestions only, but I'd like to know if I generally should stick to 
the Golden Section or if the Rule of Thirds is just as valid? Is the 
Rule of Thirds just meant as an easy approximation to the Golden 
Section?