Been watching this thread develop for the last few days and I must admit when I saw the origial news story I did think the same as Bramshott - this would not be a story if it were boys outperforming.
Like cory I used to lecture and agree with what she said but my experience was mainly to graduate (MBA) students and in general I would say women were less confident than men in classroom discussion which is a staple of the MBA teaching routine. Women also tended to far underestimate their actual ability. I used to make considerable effort trying to encourage women to speak to me and the class about their experiences and opinions while equally I had to put a fair amount of effort in to get men to shut up. Men tended to be over confident in giving opinons and answers.
Often I found women preferred to come and talk to me after the class after thay had thought for a while about what they wanted to say. Some men did too but it was noticeable how many women preferred to do it rather than ask questions in class time.
My experience of marking both formal exam papers and also project work was that women and men faired equally well overall. I used to do specific statistical tests to make sure that both the mean and the standard deviation of my marking of men and women was not being unconciously biased by male and female styles. I did not find a systematic under or over perfomance by one sex over the other.
I think that the typical regime I had of 50% of the marks going to project work and 50% going to formal exams probably did even out the natural sex differences in performance in those two types of assessment.
It is possible that the shift to more project work at both AS level and undergraduate level has favoured women over men.
That said, employers do undervalue women and if women undervalue themselves (as I often found they did in lectures) the bias will be perpetuated and reinforced against women in the work place. It is bad for the economy and firms to see female talent going to waste.
My experience is that women are not intellectually less (or more) capable than men in the classroom setting but they do I think have different talents and ways of working that complement men's talents and offset some of the downsides of men's working modes such as over confidence.