There was a study done a couple of years ago by a university in the States about the differences in men and women in sport. (It's online somewhere if you don't get out much)
The important differences being that with everything taken into consideration, height, weight, body mass etc, when it came to speed events women were at best 10% behind men, and in strength events the difference was 15%.
The biggest and most important difference as far as cricket is concerned is reaction time, women are on average 22% slower than men in that department, 22% may sound a lot but in real terms its only milliseconds, but milliseconds is the difference between someone who can bat well and someone who couldn't hit a cows arse with a shovel, hence the frequently used term "timing".
So, unless evolution decides to speed up and change the female form in the next few years, I don't think we'll see women playing alongside men in the Championship in our lifetime.
The study was done by the University of Michigan should anyone like to look it up.