Dennis Mangan is skeptical of Bruce Charlton's claim that IQ is inversely related to creativity. Dr. Charlton makes the reasonable argument that centuries of civilization selected for intelligence and docility, traits which have become the mark of a civilized man.
A 2005 meta-analysis estimated that the correlation between intelligence and creativity is .17--weak but positive.
Much of the old research did not use structural equation modeling--an advanced method that allows one to estimate g (general intelligence). Using this method, Silvia (2008) found a moderate-to-strong positive association which is reduced some when openness to experience is controlled. In other words, part of the reason why IQ and creativity tend to go together is that the trait of openness is linked to both.
Caveats: The sample was of college students--mostly women--of unidentified race (it's not unusual for race-o-phobic psychologists to treat race/ethnicity as unimportant). The results would probably be stronger if the sample were more diverse on IQ and creativity. Of course, the results do not necessarily apply to other populations.