You wrote "The standard work is
The Bell Curve" and that tells us that you haven't been reading on the subject since 1994, because
The Bell Curve has long since been supplanted as a source on the subject. (It was decried as stupid by anyone who knew genetics from the moment it was published.) More recent sources on the issues of income, race, IQ, and related issues can be found in the publications of Eric Turkheimer, recent president of the Behavior Genetics Association, most of which he kindly shares as free full text on his faculty website.
http://people.virginia.edu/~ent3c/vita1_turkheimer.htm
Note particularly his recent co-authored publication
Nisbett, R. E., Aronson, J., Blair, C., Dickens, W., Flynn, J., Halpern, D. F., & Turkheimer, E. (2012). Group differences in IQ are best understood as environmental in origin. American Psychologist, 67, 503-504.
http://people.virginia.edu/~ent3c/papers2/nisbett2012groupdi...
that directly disagrees with The Bell Curve on several points and yet was published in a leading journal for professional psychologists.
Many, many other researchers have gone beyond the amateur level of research published in the popular book The Bell Curve to grapple with the issues that book brought up and refute it. A good bibliopraphy on the general subject can be found in Wikipedia userspace at
http://en.wikipedia.org/wiki/User:WeijiBaikeBianji/Intellige...
with plenty of recommendations for current reading in reliable sources.