Yglesias makes fun of a not-especially-great article in the NYT on The Great Gatsby. The article is wrong insomuch as the people quoted unreflectively seek after their 'green light;' but the commenters who stake Gatsby as a critique of the American Dream are wrong, too.
I take the point of Gatsby to be that money doesn't change very much about a person. Tom Buchanan would be nasty and horrible even if he were poor--all his money does is permit him to be awful in more particular ways; the same is true for Jordan and her inflated self-conception. Gatsby is great and tragic: he pulls himself up to become what he is, but has a vacuity he is never able to do away with (the books on his shelf he's never read, Nick's reaction on reading Gatsby's program for self-improvement). Even so, he's 'worth the whole damn lot of them put together.' He doesn't fail because he's rich, he fails because he's a Middle Westerner trying to measure his success by the standards of the east. That's not a judgment of the American Dream, that's a judgment about the fitness of people for certain times and milieux.