I think its way too early for any of this but if Michael Caine said an exec told him I'm inclined to believe it. It's likely though that the exec could have been talking about his hopes or rough plans for what he'd like to see happen ie they will try to approach Depp/Hoffman.
All I know is, Johnny Depp and Philip Seymour Hoffman, with Bale and Nolan returning = me there on opening day.
I'll watch Depp in anything but Hoffman is a really intriguing choice. I think, handled in a more menacing manner, this guy has real screen presence. I can imagine some really crackling scenes between him and Christian Bale. Much better option than rolly-polly guys with perpetually goofy looks on their face (Bob Hoskins
I like the idea of Riddler as a profiler or maybe a private investigator, or something, putting his brilliance to use in tracking down Batman's identity. In fact, maybe his lack of progress, batman giving him the slip too many times, frustrates him and he falls down the slippery slope, doing more and more drastic things to root out batman, eventually staging big horrible crimes to draw Batman out. Tie in with Penguin somehow. Another intriguing choice for Riddler would be Guy Pierce who has a relationship with Nolan.