I was exploring a world generated in the newest snapshot (14w11b) and in the water of a swamp biome an endermite was rotating through an angle of 90 degrees what seemed like about 5 times a second (it was rotating really fast).

Decided to quit and re-load the world after I got a screenshot of it and when I got back in the endermite was gone.

Wish I got a video of it ... not sure how much use it would have been though,