That confirmation has hit the 'net overnight though, after Rocksteady's marketing manager, Dax Ginn, confirmed the character's inclusion in a newspaper interview.
ArkhamCity.co.uk has a transcript of Ginn's interview in the Australian Sunday Herald, which details of a few tid-bits about the character's direction: "The way that penguin has always been portrayed is as quite an aristocratic, well-spoken gentleman who's got these twisted delusions of grandeur. So we've made him a really horrible, nasty piece of work - but still with the delusion of grandeur. He dresses well, but in a poor taste, and we've made him this brutish, brutal guy but also key into collection fascination that he's had through out the years."
We like the Penguin best when he's at his absolute filthiest. Here's hoping he's drooling all over the place and being generally reproachable in Arkham City. It wouldn't be the Penguin if he wasn't, right?