The new iPhone 4 may indeed be “the thinnest smartphone on the planet,” as Apple CEO Steve Jobs described it Monday during his Worldwide Developers Conference keynote presentation. However, it’s shaping up to be an out-of-this-world data hog — just as AT&T, playing the role of “The Biggest Loser’s” Jillian Michaels, begins weaning its customers off of all-you-can-eat data usage plans.