I think IQ tests measure cognition very well, but not meta-cognition (which IMO is way more important). This was covered in this thread and the linked article:
http://www.stevepavlina.com/forums/p...=metacognition
Past a certain point, you realize that intuition/meta-cognition completely overpowers logical thinking and reasoning; it takes so much effort to concentrate on making logical steps, and it all falls apart when you make the wrong assumptions. In ideal ivory-tower problems, they give you the correct assumptions, but in the real world, almost 100% of the time your assumptions are off one way or another
I think many of the people with high IQ also realize this meta-cognitive aspect -- they find their own shortcuts to everything, they "get" the essence of what a problem is about without having to "think" about it, etc. So I think instead of approaching intelligence from the point of view of traditional left-brain logic and cognition, it's more helpful to approach it from a holistic, intuitive, meta-cognitive right-brain way.