Well, I guess the Batman thing isn't really a Mojang thing, but still, how cool is the above screenshot. With Halloween on the way, it looks as though Minecraft is about to get a suitably terrifying update. An update that feature Witches (that you can set on fire, of course) and Bats!
The Witch is aggressive and has a magical nose that wiggles -- which brings to mind that crazy old show Bewitched! She can attack you with splashes of potion. The bats? They sleep during the day and spawn in dark caves.
The Witch will apparently remain in the Minecraft universe after Halloween.
There's a whole heap of detail on the new update on this superbly well researched Reddit post. If you're looking for more info, best to head over there.
Minecraft snapshot 12w38a released [Reddit]