I hate that wage disparity is being heralded as a gender issue. It's really a negotiating problem. My coworker and I were hired together, same position, same experience, and offered the same salary. When I was offered the position, I asked for $15,000 more and they gave it to me. My coworker didn't ask for more and is therefore now making $15,000 less than me. After six months, I asked for a raise of $5,000. He never…
I remember reading some studies that suggest that this alone, i.e. men being more likely to go and ask for a raise / negotiate their salary, can account for most of the "gender gap".
It's a complex issue and you should avoid people on either side who try to scrunch it down to one sound bite.