Perhaps American and United are competing again - at least on extras. United has just matched American's plan to start charging for the first checked bag, (yes, the first), following American's decision to adopt United's plan to start charging for the second (extra) checked bag. United will impose the $15 fee, raising perhaps $275 million a year; much like American, it exempted premium-level frequent flyers and those in first or business class. United is also raising fees on overweight and third bags by 25%. The fact that both of the nation's two largest carriers are charging the fee makes it all but certain that will soon become universal, and US Airways is expected to be the next to jump on board. Left Field talks about the United decision on Chicago Public Radio here.