I think the second The Dark Knight trailer came out in January, so i would expect it then. since its already been leaked, it would be logical to release it straight away.
my thoughts are. that i actully prefered Batman Begins to The Dark Knight. and thats because i felt BB went into a lot more depth with Bruce Wayne, TDK didnt fo into as much; this seems like it does and i'm happy with the tone of this film.
somethings i'm not happy about, but i wont bore people with that. on a side note, if that hovering vehicle is the Batwing, it looks shit!