Good question, although I don't think that the challenges or advantages are actually very significant. Most schools are skewed more heavily toward men, so in the interest of recruiting a diverse class, they're interested in bringing in women. So, all things being perfectly equal, I would guess that a woman has a slight advantage, but outside of this theoretical situation I don't think women have much of an advantage just because they're women.
Similarly, when it comes to admissions, I don't think that women are disadvantaged in any way. I've received some questions from women who have stepped out of the workforce to have children, and now want to apply to b-school. They worry that they will look soft or not focused on their careers. But I argue that they can actually put together a very compelling application (as long as they have a good "Why MBA?" answer, just like everyone else), simply because they have a unique story to tell.
In school, I don't think women are at much of a disadvantage. The only time when I personally saw some of it was when some women didn't speak up in the classroom as much as they could or should have. But in recruiting, I saw some companies give a slight preference to women (especially in male-dominated industries), so it works both ways!
Scott
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Co-Author, Your MBA Game Plan