One thing that I like about Joseph's story that I think alot of people miss is how much Potiphar trusted him. Remember that Potiphar was captian of the guard (Genesis 39:1). Joseph showed that he was a person worthy of trust and Potiphar put him in charge of his house. Obviously his wife caused some drama and I believe that Potiphar really trusted Joseph over his wife in this matter. Why because he was captian of the guard, he was also in charge of the prison. He merely transferred Joseph away from his wife (probably because of public opinion in this matter or just to keep his wife happy). Genesis 40: 3-4 shows where this prison was in Potiphar's house and that Potiphar intrusted their care and also the care of all the other inmates to Joseph. This was probably even more important then being in charge of his house since these prisoners belonged to the Pharoh. What if he sent for the chief butler and he had died? Pharoh would have been very upset.