For one, did you know that Criterion initially planned to have motorcycles vs cars? Yep, sure was planned -- and did you know that Criterion wanted to create a whole series of islands, not just the one? The devs even wanted to give players the ability to go to the moon, complete with lunar challenges for Freeburn addicts. Also: the planes thing wasn't an April Fool's joke -- the dev actually wanted to add them (and other vehicles) into the game.
Overall, it's a pretty great read, if only to show you just how committed the studio was to the game and raising the bar for DLC in general.