FALSE - Today, the answer is False. BUT - A new Florida Statute says: Every building for which a permit for new construction is issued on or after 7/1/08 and having a fossil-fuel-burning heater or appliance, a fireplace, or an attached garage shall have an operational carbon monoxide alarm installed within 10 feet of each room used for sleeping purposes.
So, new homes will soon be required to have carbon monoxide detectors, if they have gas burning appliances.
Last year, the first part of this Statute required carbon monoxide detectors be installed in public lodging areas (hotels) where the potential for carbon monoxide was present.
If you have gas burning appliances (fireplace, water heater, range, fireplace), I recommend you invest in a carbon monoxide detector. Like they say, the life it saves could be your own.