People like to throw those same numbers around a lot. I bet you many of those 42% aren't playing games like SWTOR and the like. I'd say it's a much smaller percentage that play MMOs and FPSs and such.
I wouldn't be too sure of that. I've played WoW since release and run across many families, couples, and single ladies that play. Could it be somewhat less than 42%, perhaps, but I'd be willing to wager that more play MMOs like STWOR and WoW than FPS games like MW. In any event the number of women players is significant and has been steadily increasing.