What led you to think there would be a Criterion release of Dark Knight?
Criterion and a few other labels are specialist independent distributors. They have to licence the films individually and commission the features themselves, hence why they are expensive. They usually concentrate on old films that haven't been restored or released properly by the big distributors, or new films by smaller studios who capitalise on Criterion's unique presentations (Wes Anderson's films). In the past they have released a handful of well known big modern films, like Robocop, Silence Of The Lambs, The Rock and Armageddon, but these are rare and I doubt you'll see any more. They saw a niche market for these popular films to be released with better presentations than the original studios who licensed them to do it, but nowadays those studios are more savvy and get on with releasing ultimate editions immediately. Not to mention in this digital age, new films don't need Criterion's attention to restoration.
I wouldn't put it past them to catch on to an undervalued brand new film and release an awesome edition of it, but credit where it's due, the Dark Knight Blu-Ray is pretty good already.
Criterion use a spine number system and the website is thorough so if it isn't in the list, they haven't done it.
http://www.criterion.com/library/list_view?p=1&pp=all&s=spine
