Just before the white light cascades over everything, I can't help thinking that what's going through Ben's mind is, "I'm going to die. Please forgive me." He knows he's going to be banished from the Island... and he doesn't know where he'll be sent to. He could wind up anywhere in the world, or anywhere above it or inside it. The next moment could find him on the floor of the Atlantic Ocean, for all the good that it would do him. I like to believe that this was a "leap of faith" moment for Ben, and that when we see him materialize in the Tunisian desert that it was Jacob's doing.
Everything is orchestrated flawlessly in this scene, from Michael Emerson's performance, to the sets, to how we see the affect that Ben's action has throughout the area of the Island. And Michael Giacchino's music here: I will buy the Lost Season 4 soundtrack just for this, if/when it comes out.
In the two and a half seasons that he's been a character on Lost, this was the definitive moment for Benjamin Linus. And it's being widely agreed that this was the most amazing single scene of this television season.
So here it is courtesy of YouTube: Benjamin Linus working the frozen donkey wheel, and using it to move the Island...