Former Talking Brains West grad student, Colin Humphries, in collaboration with Einat Liebenthal and Jeff Binder, has recently published the best study yet of the tonotopic organization of human auditory cortex. They found evidence of frequency sensitive gradients, but oriented differently than previous work has suggested. Definitely worth a look.
Humphries, C., Liebenthal, E., & Binder, J. (2010). Tonotopic organization of human auditory cortex NeuroImage DOI: 10.1016/j.neuroimage.2010.01.046