Who would have guessed?
Mike Huckabee, Bill Richardson and Hillary Clinton run the most gender-balanced campaigns, while Rudy Giuliani runs the most male-dominated. Of course, Giuliani is staffing his campaign with right-wing nutjobs like Norman Podhoretz and Daniel Pipes, so maybe there are just fewer women in that pool to choose from (Michelle Malkin and Ann Coulter can only do so much).
Thanks to Jess for the link.