Dragon

Dragons are a planned mob. Notch hinted during the Spider Jockey update that he will add Dragons to the game. Dragons may also be able to fly or breathe fire. Notch confirmed in his Twitter that he will definitely add a form of flying transportation. There is a chance that Dragons may be able to be ridden in a similar manner to pigs, which would indicate that Dragons are passive or may need to be tamed before being ridden. It is also mentioned that dragon lairs may be an addition.