It's been asked whether the Joker-centric footage that will be shown ahead of the IMAX version of I Am Legend will be something specifically produced for that or if it will be an excerpt from the actual movie. The answer is that the footage (which comes out in December) is the first 5 minutes from The Dark Knight. I'd heard 7 minutes, but whatever - at least now we know what it is.
Of more importance, Chris Nolan gives a hint as to the plot of the movie as related to The Joker, and I think it is VERY good news!
From director Chris Nolan:
"[THE DARK KNIGHT] is not 'The Joker Begins.' We did not want to tell how The Joker became what he is. In those five minutes [of the prologue], we show how The Joker goes from being a small-time crook to Gotham‘s greatest villain. It‘s like 'The Rise of the Joker.'"
I don't know about you but I think this is excellent news. One of the complaints a lot of folks have lately about superhero movies is how they seem to be mired in origin stories. Coming into the story with The Joker established as who he is within the first five minutes will allow things to get into gear immediately.
This is more great news as far as I'm concerned. Or would you rather have more of the movie spent showing how he becomes who he is?
Source: Batman on Film