Gender Gap in Earning

From Men Don't Have it Easy Either:[Emphasis mine]

6. Women earn less for the same work than men.
False: For the same work, women earn, on average, the same. According to the book, Why Men Earn More, based on a decade of analysis of government and other statistics, reasons for the "women earn 80 cents on the dollar" figure include that men more often choose careers that are more dangerous (e.g., police and firefighter), uncomfortable (from sewer repairer to crop duster), isolating and difficult (e.g., engineer and programmer) and work longer hours. The average man who says he works full-time works more than six hours a week longer than the average woman who says she works full-time. In addition, men are more likely to work evenings and weekends. For a promotion, more men are willing to move to places that fewer people desire. An offshore oil rig in Montgomery, Alabama, anyone?
Even comparing salaries in the same career tends to be biased against men. For example the Bureau of Labor Statistics lumps together all medical doctors but men are more likely to pursue higher-stress specializations with unpredictable hours such as surgeon whereas women are more likely to be a lower-stress pediatrician, and thus women physician salaries are lower.
Despite all this, today, unmarried women who have never had a child earn 113% of what men earn. That suggests that for the same nature, quantity, and quality of work, women likely earn more than men, and only when a woman makes the choice to have children and thus, on average, is less focused on her work life, does that woman's overpayment dissipate.
The good news for women is that when they make the same career choices as men, they can earn at least as much.

The article has much more info on how the world is getting difficult for men as opposed to women. A must read. [Via Ben]