Remembering (early 2000s) my comp sci classes (and to a lesser degree higher math) I was pretty heavily outnumbered (compared to my classmates back then I'm black), the few girls in class had it even worse. As soon as I went to one of my electives (even something science like Bio or Chem) the makeup changed, e.g. enter the arts department and I was once again outnumbered but then again so were the white dudes (mostly women with a decent mix but still dominated by white chicks).
While I have no issues with diversity (I stand to benefit), I fail to see how facebook and family can do much about this other than they are currently doing (the various competions or http://tech.slashdot.org/story...). They could just hire the applicable minorities and have them stand around just to make up numbers, but I don't think that helps anyone.
I guess in their defense these companies should post the matching numbers of the diversity of the applicants, problem is that is near impossible due to not everyone gets called in for an interview and it would most definitely get called racist to require your resume to include your skin color (sex can probably be guessed with a high degree of accuracy).