My theory is based on the third opening of Naruto. In one sequence you see the three legendary ninjas. All of them look the same age, but when you see the latest episodes you can notice a very significant age difference between Jiraiya and Orochimaru. I would not be surprised if the third sanin would also be old. The whole point of this post is that I think that Orochimaru has a special Jutsu that allows him to change bodies at will. Similar to what Ino has but this thing is permanent. It would not be too hard for Orochimaru to change the face of the body with one of the jutsus he has taught Kabuto.

What do you think? This is all speculation and I haven't read the manga or know anything past episode 64.