Airbus beat Boeing to the punch and flew the first commercial aircraft using an alternative fuel in one engine. The really interesting thing is the two airlines are using different alternative fuels in their test flights.
Boeing announced in January they would test an alternative fuel in one engine of a 747, but did not disclose what that fuel would be. They did, however, talk a great deal about an algae-derived fuel, without being specific.
Airbus, meanwhile, said it used a liquid fuel processed from gas (Gas to Liquids – GTL), mixed with regular jet fuel in the number one engine. The flight, from Filton, UK to Toulouse, France, took three hours. The plane is powered by four Rolls Royce Trent 900 engines, and said to be the most fuel efficient in the air today.
Boeing, meanwhile had planned their test in late February, as explained in this story: Algae-Based Biofuel to Power Virgin Atlantic 747 Jet?, filed on Jan. 15.