This was an article in my RSS feed on my homepage. The article is by Jo Ann Schneider Farris at About.com. It's an interesting read, and I learned some things that I never knew.
Madge Syers was the first woman that competed against men at the 1902 World Figure Skating Championships. There wasn't any rules in 1902 that stated women couldn't compete against men. It brought about the "womens only" that was added after she competed because it was decided that judges couldn't fairly judge or compare women and men skaters.
I bet it would be pretty interesting if the rules hadn't changed and women could still compete against men. It's just a thought, but I believe not so far-fetched. The only hold back I could see is women trying to do the Quad. Men might have to add a few more moves and spins like the Ina Bauer, the Biellman spin/spiral, and the spiral, etc., but that wouldn't be much of a problem.