The last conversation Picket had with Juliet before she shot him was very interesting. When she told him that Ben had ordered her to release Sawyer and Kate he replied-
"I know Ben would rather die than let them go." (or something close to that)
He really seemed to believe what he was saying. Why would that be the case? Why would Ben be so determined to keep them around?
Obviously, he would rather not have the other losties know their true location...but to prefer his own death seems pretty extreme. Juliet didn't even really seem to challenge what he said. Did he really tell her to let them go, or was it another deception?