Kotaku's Michael McWhertor is in L.A. for tonight's video game awards. He says he just caught up with Adrian Ripburger Mark Hamill, who told him he was asked to do a trailer for a sequel to Batman: Arkham Asylum.
Mike says he went to the Rocksteady guys for confirmation, who said only "they're working on something really exciting."
Taken literally, this confirms a trailer, not an actual game in development. If it is a game, that's hardly a shock - an incredibly successful, well reviewed game paired with a label that loves sequels, go figure. So, from Col. Blair's Luke Skywalker's mouth to your ears, there you go.