I'm going to say it again, because I'm starting to expect this to happen. I have no evidence to support it, but just call it a feeling.
At the end of January, in time to coincide with the release of Smokin' Aces, Ryan Reynolds will be announced as Harvey Dent.
He's unconventional, as he's most well-known as a comedic actor. But, lately, he's been steping away from pure comedies, i.e. Smokin' Aces, Blade Trinity, The Amityville Horror.
David Goyer, co-writer of Batman Begins and The Dark Knight, loves Reynolds. He cast him in Blade Trinity, and wants him for the role of The Flash. Goyer could have easily recommended Reynolds to Nolan.
Reynolds has the charm and charisma to be Dent, easily. Plus, Dent is supposed to be a good-looking guy, and the ladies seem to love Reynolds. And, as a heterosexual man, I can admit he's a good-lookin' fella.
In the comics, and hopefully an element they'll keep in the movie, Gordon thought Dent was Batman for a while. That means Dent has to be tall, athletic, and intense. As far as tall and athletic, Reynolds stands at just under 6'3, and he has a very muscular build.
As intense goes, Reynolds has been working on proving that. He's been good, but he hasn't had the material to show off completely what he can do. Blade Trinity and The Amityville Horror showed some range, but Smokin' Aces will show more of it. The only review I've seen for the flick calls Reynolds the closest thing the movie has to a leading man, and he pulls it off with flying colors. Not only that, he shares most of his screen time with Ray Liotta, a proven and great actor. For Reynolds to bounce off Liotta without problems in a dramatic role, he's got to have some range.
The guy is a rising star, proving himself to be pretty popular with the movie-going public. And, with Reynolds looking for dramatic roles to further prove his chops, The Dark Knight seems right up his alley. Not only does he get to attach his name to a powerful franchise, he gets to act with some of the best actors around - Bale, Ledger, Caine, Oldman, Freeman.
Again, I've pulled this information from nowhere. It's just a theory that kind of came to me. Ryan Reynolds will be Harvey Dent / Two-Face.