Apparently in error, a number of ComiXology readers have stumbled upon the image at right, which features the new-look Joker dancing with Batman's blood-soaked costume on what is purported to be the cover of Batman #17.
In case there was any doubt as to its authenticity, a fan pointed it out to series artist Greg Capullo on Twitter, who responded "Where did you get that?" and nothing else.
Which sounds like a confirmation, although it obviously may not be.
Poor Capullo; he has been trying very hard to keep The Joker's gruesome new look under wraps, but whatever he does, it seems that somebody (either officially or not) is always releasing these images way out ahead of time.