Sneaky, sneaky, sneaky. An unannounced (but apparently official) exclusive to the PS3 version of Batman: Arkham Asylum will be the ability to play as The Joker in the Challenge Maps - and Kotaku even has a screenshot of one of the signs.
Several readers sent us in blurry photos of the new sign, which has appeared in various spots throughout the Home service today, featuring a grinning Joker (the best kind) and boasting exclusive challenge levels for the PS3 version in which players will be able to take control of the clown prince of crime. I hopped online and snapped my own shot, but appreciate the efforts of our readers to bring this story to light.
I contacted public relations for the game, who couldn't offer me any details on the exclusive, or whether or not the Xbox 360 version would be getting something similar. In fact, the man I spoke to seemed rather shocked that the ad had already gone up. Whoops.