Before I go any further, this post contains a spoiler for the forthcoming Batman movie.

Aaron Eckhart, the actor portraying Gotham D.A. Harvey Dent (The man that eventually becomes the villian Two-Face) told DarkHorizons.com about the fate of his character.

In the comics, Harvey Dent, a driven D.A. that often works with Batman and Commisioner Gordon, has acid thrown in his face by a mobster. Batman deflected some of it, resulting in only half of Dent’s face being hit by the acid. The severe scarring shattered the psyche of Dent, turning him into an unpredictable psychopath that often makes choices by flipping a two-headed coin, one side of which has been slashed.

For some time now, there has been speculation as to whether or not the transformation occurs in the forthcoming The Dark Knight.

You can read the entire transcript on Dark Horizons, but here is the quote that tells us whether or not Two-Face is in The Dark Knight:
Eckhart: Well I will only say that in Batman I am both Harvey Dent and Harvey Two-Face.

To Mtv he said:I play Harvet Dent. Harvey Two-Face. They are both in the movie.

So now we know. I am guessing that we will only see a glimpse of Two-Face. Maybe have the transformation occur, but little else.

It is almost certain that Two-Face will play a major role in the third film.