A bunch of (US-centric) links:
Jennifer Hunt's NBER working paper: Why Do Women Leave Science and Engineering? (pdf):
I use the 1993 and 2003 National Surveys of College Graduates to examine the higher exit rate of women compared to men from science and engineering relative to other fields. I find that the higher relative exit rate is driven by engineering rather than science, and show that 60% of the gap can be explained by the relatively greater exit rate from engineering of women dissatisfied with pay and promotion opportunities. Contrary to the existing literature, I find that family–related constraints and dissatisfaction with working conditions are only secondary factors. My results differ due to my use of non–science and engineering fields as a comparison group. The relative exit rate by gender from engineering does not differ from that of other fields once women's relatively high exit rates from male fields generally is taken into account.
A set of inter-related stories in NYTimes: Bias Called Persistent for Women in Sciences, After Harvard Controversy, Conditions Change but Reputation Lingers, and Risk and Opportunity for Women in 21st Century.
On the general subject of claims for which there does not does not exist relevant empirical evidence, are there any published studies (or any research projects currently underway) to explore the connection Tierney, Summers, et al. seem to assume between being in the extreme right tail of laboratory measures of mathematical and scientific aptitude (like the math section of the Scholastic Aptitude Test) and having the chops to "to get a doctorate in science or to win tenure at a top university"? Because it strikes me as likely that there may be some crucial competencies required to do cutting-edge scientific research that the SAT just doesn't measure.
Indeed, if tests like the SAT are such good measures of scientific potential, couldn't universities and federal funders of scientific research save themselves a lot of time by only training, hiring, and funding (potential) scientists with sufficiently high SAT scores, regardless of gender? Is there reason to believe that approach would deliver excellent scientific research without relying on such an "excess" of graduate students and postdocs?