Although the idea that IQ only enables creativity "up to IQ 120" is widespread (and repeated in pop-psych books such as those of Gladwell etc.), large scale studies of giftedness reliably find that the IQ and creativity are associated even at the very highest-extremes of ability. IQ is linearly related to creative achievement across the range (Wai et al., 2005).
A reanalysis by Silvia (2008) of the Wallach and Kogan (1965) paper which originated the idea of a 120 IQ "threshold" found that the original data do not sustain the idea of a critical level.
The suggestion above by @BenBrocka that creativity and IQ are not linked (or only weakly associated) is not supported by the weight of evidence. Nusbaum & Silvia (2011), for instance show that IQ accounts for around 40% of creativity.
Nusbaum, E. C., & Silvia, P. J. (2011). Are intelligence and creativity really so different?: Fluid intelligence, executive processes, and strategy use in divergent thinking. Intelligence, 39(1), 36-45. pdf
Silvia, Paul J. (2008) Creativity and intelligence revisited: A latent variable analysis of Wallach and Kogan (1965). Creativity Research Journal 20. 34-39. pdf.
Wai, J., Lubinski, D., & Benbow, C. P. (2005). Creativity and occupational accomplishments among intellectually precocious youths: an age 13 to age 33 longitudinal study. Journal of Educational Psychology, 97, 484. pdf