Actually, it IS possible to move an entire island
So in the most recent episode of Lost, Christian Shephard told Locke that the only way they can save the island from the invaders is if they, um, move it. Yeah, that's right, move the island. Thanks Doctor Shephard, I'll get right on that.
But viewers thinking that this was some crazy thing that could only happen on television and in the movies are...well, probably right. But in this Popular Mechanics article, the author of the book Physics of the Impossible says that it actually could be done. Michio Kaku says that it sounds like they're going to use the electromagnetic properties of the island and the Casmir Effect to "open a transferable wormhole to different points in time and space."
(Hold on a second while I go take two Advil.)
OK, I'm back. Kaku says that the Casmir Effect and transferable wormholes are real. It's possible that a black hole could be opened on the island, leading to other times and places. But because it's unstable, it's a one-way thing, which kinda sucks.
As for moving something really big like an entire island, that would involve quantum teleportation. I don't think I could explain that (it has to do with "science"), so just click on the link above and enjoy.