I've read a very good book on the subject, Pink Brain Blue Brain, in which the author writes about what are the really physical differences between genders and which are social differences (basically nature vs. nurture). A good read for anyone trying to understand where science stands as of today on the gender gap questions.

The main theme of the book is, there are differences, but not as dramatic between genders as between two individuals; and much of the differences may be alleviated by paying attention to stereotypes when raising or educating children.