COWS AND RICE ARE NOT USELESS!
Sorry about shouting. But Cows and Rice are useful. There isn't one thing on the map that is now worthless. Although... I haven't figured out how, after tech obsoletes a luxury (like fur, ivory, whale), that the AI wants to trade you that for something it needs from you like Iron, Wine, Gold, Wheat, Crab, etc.
I like Civ4. Once they tighten up the code, this is going to be a very nice thing.