Updated October 20: Geoff Johns has now tweeted the finished, full color version of the variant cover, seen here.
Original Story: Artist Gary Frank has tweeted the pencils for his variant cover for the yet-to-be solicted Doomsday Clock #5, featuring the Joker (or one of the three Jokers) applying some make-up.
Since the image is black and white, it's hard to tell what part of his trademark look Joker is applying - or whether that's some kind of hint at a larger portion of the narrative. So far, the Joker's inclusion in the story has not been revealed.
DC characters already known to take part in the Geoff Johns-written Superman/Watchmen centric crossover are Superman, Batman, and Lex Luthor.
Doomsday Clock #1 is due out on shelves November 22, with #2 following in December. This means that, unless any delays or breaks arise, Doomsday Clock #5 will likely be solicited for March.