Nothing but a rumour of course, but I'm so in love with this idea that I'll actually be disappointed if it doesn't come true (that is of course until I see Batman 3 anyways, and am still blown away).
Joseph Gordon-Levitt as The Riddler rumour
(also for those talking about Under the Red Hood...it's not very good if you're a huge bat-fan. Bender as the Joker falls completely flat, while Batman's voice is passable, but it should still be Kevin Conroy).
I'm still heart-broken that Mark Hamill's final performance as the Joker is going to be in Arkham Asylum 2.