What happened to Harvey Dent?

Dark Knight left the audience with many questions. One of them was, "Is Harvey Dent dead or alive?" Well, Aaron Eckhart was in an interview earlier this week where he answered the question with two words..."He's dead". He said that he asked Christopher Nolan is he would be coming back in the third and he said the there was no chance. This was disappointing for me to hear because I think that Two-Face should have been more involved in the movies...guess not.