Here is the poop straight from the horse's mouth, (the fine folks at your friendly neighborhood TSA).

Print this out and keep in your carry on baggage. Follow it to the letter and you should not face much in the way of prison time. <img src="/images/graemlins/shocked.gif" alt="" />

http://www.tsa.gov/public/display?theme=177

http://www.tsa.gov/interweb/assetlibrary/Permitted_Prohibited_9_6_2005.pdf

Good luck, TR