It's been done, but below Conference level:
http://news.bbc.co.uk/sport1/hi/footbal ... 894496.stmInterestingly enough, the "manageress" in question Donna Powell (not related to Hope Powell as far as I'm aware), felt that the biggest problem she faced was trying to get her instructions across from the touchline, because she said her voice wasn't loud enough to project. That obviously wouldn't be the case with all women, I'm sure we've all had experience of a healthy set of female lungs at one stage or another.
There is nothing about women that would make them inferior managers in an ideal world. Posts claiming that women's football is tactically different to men's do not make a convincing argument - women can watch men's football as much as all of us. If we have views on tactics then so can they. However, it would be the current politics that would stop it happening. Too many players have monstrous egos and wouldn't accept it, if there's was the first club of that stature to try it. If a woman had proved herself, getting a team promoted from League 1 or 2 up to the Championship, or Prem, then that would maybe open the door.
As it is, football must be the most old-fashioned sport when it comes to sexist views. Even female physios get whistled at!