It looks like another bright new day for Don Draper. Don, of course, is a master of reinvention, as you'd expect from someone who invented himself in the first place. But with Sunday's Season 4 premiere, the Emmy-dominating series that gave him birth is proving to be just as adept at changing course without diminishing its appeal or fundamentally altering its core — and in a summer in which good TV news has been sparse, that's a shining news flash indeed.