I'm using the latest version of Zen. In the product listing variables, there are no definitions in the edits and no matter what I put in there, it doesn't change anything. For instance, I do not want the weight to show in the product listing. I don't mind if a weight shows in the cart. Here's the way they are set now:

Display Product Image 1
Display Product Manufacturer Name 0
Display Product Model 0
Display Product Name 2
Display Product Price/Add to Cart 3
Display Product Quantity 0
Display Product Weight 0