If you think about it, DKR would make a great video game on so many levels. Even if the video game weren't intended to match the brilliance of the book in terms of the writing and the feel, it would still really work.
It's mostly about the way the story builds: from Harvey Dent to the Mutants to the Joker through to the end. There's also potential for a number of boss-fights, and it would be a great free-roaming Gotham with all the random crimes.
What do you think?