http://www.epa.gov/otaq/cert/factshts/catcvrts.pdf
All you ever wanted to know about the US Gubment and Catalytic converters.
Let me add this: If you ever have the need to have an old cat cut out or replaced for any reason- make sure that you either keep it or get some $$$$ compensation from the shop that did the work if you allow them to keep it. I know that Platinum and Rhodium are at record high prices on the precious metals markets, and even thought there's not much in the typical converter, it doesnt' take much at ~$2k per ounce to be worth some good money.
PM or email me if you have some old converters you want to get rid of, I have a couple of good places that pay good $$$$ for them.
Bret.