The gender gap argument never held much weight for me... there are a number of studies saying that if you adjust for a certain number of factors, the gap is pretty narrow (IE women who didn't take time off to have kids, etc)
While women now make up a majority of college students, there is also a factor of what they study. They make up just a third of top-tier b-schools, for one thing, and a smaller number at engineering schools.
Its not really fair to adjust for factors such as not taking time off to have kids. There are a number of biological reasons why it makes sense for women to be more involved in the early stages of rearing children than men (for example - only women can breastfeed).
For career focused women it is a very big problem that many career paths don't allow an easy way to take time off (or even just slow down a little bit) for children and then come back to reasonable opportunities.
The study from 2009 is indeed a publication from 2009. When I trace it to yet another web site, I find that the citation for the US figure is from a study of 1998. But it mentions "social construction", so I guess it's scholarly.
While women now make up a majority of college students, there is also a factor of what they study. They make up just a third of top-tier b-schools, for one thing, and a smaller number at engineering schools.
Here's an interesting study: Women don't negotiate... http://neweconomist.blogs.com/new_economist/2006/07/menstrua...