In Vanilla, I was regularly one of two females (at least who spoke) in the guild - first was a tank with Thunderfury on Alleria; second was half of a husband/wife duo who was a terrible healer on Thrall; third was a shadow priest on Blackhand - with a bonus trial that was basically the same as the Thrall woman, only a terrible dps. She rolled a 99 on the Zulian Tiger, I rolled a 98... the next day she was kicked from the guild for poor performance and I wouldn't see it drop again until a week before it was removed (I thankfully was running it solo).

But that was all Horde. I had a max level ally Druid to play with friends I made on Thrall and that guild had like 8 women, it was a nice change of pace. In TBC and Wrath, any guild I was in routinely contained more women. I was gone most of Cata, but the same was true in my MoP guild as well.