It depends on which type of lighter. TSA will no longer ban common lighters in carry-on luggage as of August 4, 2007. Torch lighters, which create a thin, needle-like flame and are often used for cigars, continue to be banned in the cabin.
Lighters without fuel are permitted in checked baggage. Lighters with fuel are prohibited in checked baggage, unless they adhere to the Department of Transportation (DOT) exemption, which allows up to two fueled lighters if properly enclosed in a DOT approved case. If you are uncertain as to whether your lighter is prohibited, please leave it at home.
One box of safety (non-strike anywhere) matches are permitted as carry-on items, but all matches are prohibited in checked baggage.