I'm a bit late with this one but those crafty guys at Kotaku have been snooping on Pandemic staff and their personal blogs to suss out some Dark Knight media, and it looks like they have scored some success.
Michael Pryor, 3D environment artist at Pandemic Studios Brisbane, had some really great looking screen shots of what we can safely assume are from the Dark Knight game. It probably hasn't helped that Michael has pulled down those shots from his blog, but Kotaku saved some smaller versions of it and hosted it on their site. It looks absolutely outstanding.