http://twitter.com/#!/notch/status/116449292859883520 It's a snowman that shoots at creepers, spider, zombies, and skeletons. Not sure about passive mobs.
Looks derpy, and is, IMO, a stupid way to put in something rather useful. What I'm saying: it looks terrible (esp. the face), the idea of a snowman killing aggressive creatures is ridiculous, but it would be interesting to have a mob that kills aggressive mobs (as long as it doesn't also kill your wolf companions).
Yea the face is pretty shitty, but it would be nice to see big and small snowmen (abominable snowman comes to mind).