As from 1st November 2009, Air France and KLM wil start charging economy class passengers who carry 2 pieces of luggage on transatlantic flights a fee for the 2nd piece of luggage.

2nd Bag Fees

a) General:
Customers will be charged EUR 50 or its local equivalent when departing
from countries in Europe.
Customers will be charged USD 50 when departing the U.S.

b) The following customers will be exempt from the second bag fee:
First and Business Class customers
SkyTeam Elite Plus & Elite customers
Active U.S. duty military members traveling on orders
Customers travelling on Marine/Seamen fares

c) Children under 2 years of age (not occupying a seat):
retain their hand baggage allowance
can continue to check-in one piece of baggage, weighing up to 10 kgs
can also take a fully collapsible stroller on board at no charge.

d) Customers with reduced mobility
may continue to travel with their medical equipment.
In addition, they may be allowed to check-in one additional piece
weighing up to 23 kgs.

(*) Countries in IATA Europe include:
Albania, Algeria, Andorra, Armenia, Austria, Azerbaijan, Belarus, Belgium,
Bosnia-Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark,
Estonia, Faeroe Islands, Finland, France, Georgia, Germany, Greece, Gibraltar,
Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg,
Macedonia, Malta, Moldavia, Monaco, Montenegro, Morocco, the Netherlands,
Norway, Poland, Portugal, Romania, Russia, San Marino, Serbia, Slovakia,
Slovenia, Spain, Sweden, Switzerland, Tunisia, Turkey, the Ukraine, the United
Kingdom.
Note that Libya and Israel are excluded.