Comic Book Movie is reporting that an inside source from Warner Bros revelaed the stars of Christopher Nolan's latest movie Inception: Joseph Gordon-Levitt, Leonardo DiCaprio, and Tom Hardy are all competing for the role of The Riddler in Batman 3.
Apparently, the studio is especially keen on allowing Nolan to hire one of the actors because of the extra publicity and attention it would bring to the movie (as did Christian Bale re-teaming with Christopher Nolan in The Prestige for example) while the fact they were all praised for their performances also plays a part.
As with any rumor from an "inside source," it's best to take this with a pinch of salt. It's already been reported that Levitt is in the running for this role, but seeing Inception, I am leaning more and more towards Hardy as the best fit to play the Riddler. Regardless it is nice that Nolan is looking at three individuals that will play the role very, very well.