So far, we have seen Charlie and Libby telling/showing Desmond and Hurley the Original Timeline. At first I thought it was only dead people who had this ability. Who's next on the list? Locke.
But as it turns out, this just adds to one of my theories regarding the turning of the failsafe key. Desmond turned the key. Charlie was nearby. Locke was also inside the Swan when this occured.
Libby, uhm. Died in the swan. I'm not sure where Hurley fits in. He must have been nearby because he is the one who gave Desmond a tshirt after finding him naked in the jungle.