The second checked bag is still $25.
United isn't the only airline charging for checked bags. American Airlines and U.S. Airways are also charging domestic economy class travelers $15 for the first bag and $25 for the second bag. A similar fee goes into effect for Northwest Airline passengers on August 28.
Delta, Continental, JetBlue and Midwest airlines allow one checked bag per customer at no charge. All four charge domestic travelers $20-50 for the second bag.
Southwest Airlines lets passengers have two checked bags without cost.
All airlines have oversized bag policies that incur extra costs if the bag weighs 51 pounds or more.