It's a weird coincidence, really, that this conversation should pop up here now. I just found out she was gay the other day when she did an interview on wow.com and offhandedly mentioned her "partner."
I know Phil Jimenez is gay, and that guy with the Spanish name I can't spell who wrote Marvel Knights 4 (Roberto Aguirre-Sarcasa?). I'm not sure who else there is in mainstream comics.