Umm, the article you linked says basically what everyone here is saying. The AI is the same at all levels, however the bonuses it receives vary by difficulty. The "cheating" that was removed amounts to advance knowledge of the map, player unit deployments, etc.
"Much of the information cheating has been removed from the game (such as knowing where a resource is before it is discovered, sending off galleys with settlers to undiscovered lands, targeting cities with fewer defenders, etc.) Further, the heuristics it uses to make decisions, such as for diplomatic demands and declarations of war, are the same ones available to the player (such as from the power chart on the Demographics screen). However, as with all versions of Civ, the AI has production and research penalties at the lower levels and bonuses at the higher levels. The level of the bonuses are lower than they have ever been before; in fact, the AI never receives any bonuses whatsoever for building wonders - a far cry from the "free AI wonders" in Civ 1. Noble and Prince are the difficulty levels where the AI's rules are closest to the human's."
There are variations in behavior based on the specific leader, and the actual behavior of the AI is more noticeable at higher levels because it can accomplish more due to the bonuses, more starting units/settlers, etc. The AI is more aggressive at higher levels because it can build more units faster. The AI trades more techs at higher levels because it can research faster and has more techs to trade.
If you want to argue with people who have very detailed understanding of how the game works, while covering your ears and screaming "you're wrong" over and over, feel free I guess. Won't make you any more right.
You get bonus points for trying to prop up Slashdot as an authoritative source for Civ4 info, though.