If we assume a normal distribution, then the median and the mean should be equal. (So should the mode.)
I thought IQs generally (were supposed to) fall into a normal distribution--a Gaussian centered at 100, with a standard deviation of around 10 points. At least, that's the way I've always heard it.
Though, I completely understand if someone wants to dispute whether IQ measures intelligence instead. Anyway, 50% of threads on APS have more drift than the median.