Indeed: http://en.wikipedia.org/wiki/Intelligence_quotient#Income

Some researchers claim "in economic terms it appears that the IQ score measures something with decreasing marginal value. It is important to have enough of it, but having lots and lots does not buy you that much."[75][76]

Other studies show that ability and performance for jobs are linearly related, such that at all IQ levels, an increase in IQ translates into a concomitant increase in performance.[77] Charles Murray, coauthor of The Bell Curve, found that IQ has a substantial effect on income independently of family background.[78]

Low IQ precludes you various job opportunities, while the correlation between high IQ and performace is more dubious, some studies show decreasing marginal value, other studies show linear correlation.

http://en.wikipedia.org/wiki/Intelligence_quotient#Real-life_accomplishments

This means that certain groups of professionally successful people have higher than average IQ, not that many higher than average IQ people become more professionally successful than average people.