Science magazine's current issue reports on a study which shows that the achievement gap in math between boys and girls has disappeared (article here (subscription required); summary and discussion on NPR). The study was based on the standardized tests administered annually to all public school students in 10 states as part of the No Child Left Behind educational reforms, as well as testing by the National Assessment of Educational Progress. In all, over 7 million scores were included in the study.
This study is heartening: not only to show that the gender gap in math has closed, but to combat gender-based stereotypes that girls have a hard-wired math deficit or that they aren't interested in learning about math.