Mm, I'd take what you hear on any tv show with a grain of salt. I've heard some amazing misinformation presented as fact.

It does appear that peace lilies are toxic -- but that they taste too bad for most cats to get enough to do damage.

Here's an article from a vet: http://www.lclarkecushingvmd.com/showpracfaq.cfm?FAQID=121&Private=0

Excerpt: "The peace lily, or Spathiphyllum patinii, is a type of houseplant that contains oxalates. Oxalates cause toxicity in animals, including cats, by causing the formation of calcium oxalate crystals in the animal's vital organs. Signs of toxicity may include excessive salivation, head shaking, pawing at the mouth, difficult breathing, vomiting, and diarrhea.

Fortunately, the peace lily plant causes pain and irritation of the oral cavity when chewed and therefore animals rarely eat enough to cause severe problems."

I've had a peace lily and cats for nearly seven years now, and haven't noticed either doing harm to the other.