Continental has hopped aboard the second-checked-bag-fee express. Passengers will now pay $45 online and $50 at the airport to check their second bag on transatlantic flights. The rule is effective immediately for travel on or after September 15.
Delta, American, and US Airways have also added this fee, and it's worth noting that Continental is a slightly better deal (and I use that term very, very loosely). Both American and US Airways charge a minimum $50, and US Airways charges $55 at the airport.
United will almost definitely match the fee, and other carriers with substantial international service (Frontier?) could follow suit.