Where "The Spirit" failed, "The Dark Knight" dominates. THAT is a great teaser poster. You could bother with posting three separate images to make one weak image for a teaser campaign or you could do THAT.
(Maybe without the bogus Photoshopping– I've never graff'ed a day in my life but those lines would be more upset by the mortar than what's happening here.)
If you're anywhere near an Imax theatre then you should consider seeing the movie there: complete with a simulated fight and some drinks in Seattle.