Thanks for the IAMS update!
Since Saturday I noticed what appears to be additional voluntary recallnow by,
Nestlé Purina
http://www.purina.com/company/press/2007/MightyDog.aspx
My bet is on heavy metal contamination in the wheat gluten... lead, mercury, cadmium, etc... The metal ions bind to the proximal convoluted tubule in the kidney and block reabsorption of glucose and electrolytes in the kidney, and can cause kidney failure. This seems most likely in an industrial setting. Look at your pet's gums to try to find a "lead line" at the gingival border. These are a deep purplish to black discoloration formed by the reaction of lead secreted in saliva with the oral flora, which produces sulfides. Gingival lines of various hues may be present in chronic toxic exposure to other metals, which react to form differently colored species... If you see one, definitely get to a vet, as the Lead line is ominous before kidney damage and kidney failure (at least in humans)... Hope this helps