They made it so everyone could vote in every category rather than just the category that pertains to them (ex: Makeup artists can vote for actors, actors can vote for lighting, etc.)
Last weekend when Margo Martindale won for a super small guest role people blamed it on the new rule.
I believe this is how the Oscar's works and why those wins are usually pretty predictable.
Jon Hamm will win for the Mad Men swan song, and that's regardless of the new rule imo. Christina Hendricks has a good chance and Elisabeth Moss will certainly not win. Their wins will be absolutely deserved, though.