Brad DeLong says the question is largely irrelevant to actual social inequality:
If inherited genetically-based IQ were the source of the extra edge that the children of the rich get in our society, than we would expect a parent with 4 times average lifetime full-time earnings–say $200,000 a year–to have a kid with a lifetime average income of $51,500 instead of the average of $50,000. But it is not $51,500. It is $150,000.
I agree with Matt that "where people end up [in our society] is substantially out of their hands" (although not by any means completely): luck and inheritance of many kinds of things are incredibly important. But this does not mean that equality of opportunity is a mirage. For most of the things that are out of the hands of the individual are not out of our collective hands at all. Genetic influence on IQ is one of the big things that are out of our collective hands–and it turns out it is really not that big a thing at all.
Frontal Cortex’s Jonah says the debate is a function of our obsession with quantifying things.