I just saw on Blastr that Mark Hamill announced yesterday that Arkham City will be his last time playing the Joker. I can understand wanting to stop after playing the character for almost 20 years, but I still think this is a sad day for Batman fans. Of all the different versions of the Joker I've seen Hamill's was second only the Heath Ledger.
I do have to wonder if they knew this when they decided to kill Mr. J at the end of Arkham City.