Why is Bruney starting? Because there may be rain and they don't want to risk Kennedy's start if the game gets called. Namely, Kennedy warms up, pitches two innings, game gets called, he can't pitch tomorrow. By starting Bruney they preserve Kennedy for a start tomorrow. Right now Bruney is dealing.
Duncan was optioned to Scranton to make room for Gonzalez. Jeter and Posada are not currently headed for the DL. At one point the Yankees considered putting Ensberg on the DL with a mysterious ankle injury he suffered Monday in order to make room for Gonzo but probably decided not to when they realized he was their third catcher and might be needed in order to avoid playing Posada if something happens to Molina.