Inside Higher Ed reviews a collection of essays from women in academia called Unfinished Agendas: New and Continuing Gender Challenges in Higher Education. The conclusion the review draws from the book is that while women are getting increasingly represented in the academy, they still aren't achieving gender parity with men.
Once women earn tenure and arrive at the institution they immediately begin getting pulled into various "service" commitments. This includes heading committees, become program coordinators, or take other leadership roles. While this is good for women that long to go into administration at a university, it often pulls female professors away from research.
I think the urge is to make sure women are represented in leadership roles but when this pulls time away from their principal mission of research, it becomes a bad thing. This particular problem with women in academia is something I've seen in other professions as well. Successful women are often overstretched. They're constantly asked to take on more commitments that they feel they cannot say no to.