Virgin America's $25 fee will apply to all flights beginning on May 5, and represents a $15 increase from its previous $10 fee. AirTran's $10 fee is lower than the other airlines' fees, and will go into effect on May 15. Business-class travelers and elite members of AirTran's A+ Rewards frequent flyer program are exempt from the new charge.
American remains the only legacy carrier that has not added an extra fee for a second bag. With even low-fare carriers hopping on the bandwagon, I expect that it's only a matter of time before this fee becomes the norm for most, if not all, airlines.