This is a theory about why "the others" kidnapped Walt and the other children on the island. Right after Walt was kidnapped on the other's boat, he was taken to the other island (alcactraz) that Jack, Kate, and Sawyer were taken to. He was probably kept in one of the cages (perhaps witnessed the polar bears figure the "fancy gizmo" out) and then was either convinced by the other's that their cause was just, or brainwashed into believing it. They probably used the same room they attempted to brainwash Karl. All of the kidnapped kids were probably subjected to this treatment and that explains why all of the kids (and Cindy) acted so oblivious to what was going on when they encountered Jack in his cage. When Walt sailed off with Michael at the end of season 2, he acted pretty weird. Maybe he knocked his dad out and drove the boat to the prison colony island to get his dad "enlightened". I bet they're still over there... "watching". And that's why when Locke needed guidence, Walt was there to see him through. Maybe they have a hologram system on the island that can make you appear wherever, whenever you want on either of the islands (wouldn't it be wild to see a holodeck hatch?). Anyway, this would factor into a lot of mysteries on the island. Like the time when Walt showed up out of nowhere to talk backwards to Shannon. He was still wearing the same wardrobe as when he was on the boat. Maybe when they got him to the other island, he broke loose, fell into the ocean and swam to shore just to find his way to the hologram deck. To him he was seeing Shannon and thinking she was actually there, that's why he shushed her. He didn't know he was in a holodeck contraption... maybe this is far fetched. But it would make for one hell of a flashback episode for Walt. Anyway, it would be great to see some more Aldo and Tom. I'm missing Mr. Friendly already.