From superherohype:
They scooped everyone on the casting of Brandon Routh in Superman Returns, and now Latino Review says The Joker has been cast in the Batman Begins sequel:
We were first to tell the world that Brandon Routh was going to be the new Superman. Now here we are at it again as we just got word from A VERY TRUSTED SOURCE that the offer last night was officially made to Heath Ledger to star as The Joker in the Batman Begins Sequel!
Umm, I don't see it frankly, but I didn't see Michael Keaton as Batman either. They could do a lot worse. I thought Paul Bettany (Firewall) who was rumored to be a frontrunner would be an excellent choice...
LF