I'm sure that there are women out there who are better programmers than I am (probably thousands of them!), but - as Camille Paglia argues - the bellcurve of female drive and talent is narrower than the bellcurve of male drive and talent. There are a lot of great sociobiological reasons for this - for example, something like 90% of women reproduce, but just 50% of guys do. Guys are driven to find and conquer hard challenges in part to gain access to fertile women. This translates into behaviors like studying programming for years, working long days, etc.

Also, it's hard not to believe that a larger percentage of men have the mathematical / analytical mindset that is a prerequisite for most IT jobs.

The politically correct will worry at this question for decades, because they're incapable of seeing the answers that are right in front of their noses.