Whaddaya know? Pass a law and make noises like you're going to enforce it and lawbreakers get out of the way. There is little in the Arizona law that isn't already on the federal books, but the feddies, as have we have all known for several administrations of both parties, never intended to enforce it. Arizona now does, and folks are opting to go home to where they came from, or to someplace else where the law isn't being enforced (New Mexico is popular, with its Dem governor).
You know, if we put big-time employers of illegals in federal prison with hefty sentences and well-publicized perp-walks (a tactic which I prefer), there would be no possibility of using amnesty to steal elections. The illegals, finding no jobs from the white-bread exploiters, would self-deport. Then we might be able to come up with a guest worker program that doesn't involve growing collectivist political power and enhancing the welfare state.