Greenlight service allows anyone to upload a game idea for community vetting, no matter what stage of production it's in – including "not real." This is an issue Valve predicted, and it has started taking measures to ban games that are obviously fake, such as anything called "Half-Life 3," and those that are patently offensive, such as "Best WTC Plane Simulator."
The only way Greenlight will succeed in its intended purpose is if its users take it seriously, and unfortunately for Steam, "the users" are "the internet." We'll keep an eye on Greenlight's progress once the initial hubbub dies down.
This is why absolute freedom is a terrible idea, people. The rabble can't be trusted with such a liberated, unchecked service, and let's be honest, most of them need to be kept on a short government-dispersed leash. That in mind, check out our new game on Steam Greenlight, Freedom Sucks: Revenge of the Plutocrats.