The annual Lorraine Mondial Air Ballons rally in Chambley-Bussieres, France, is described as the largest gathering of hot-air balloons in the world. It attracted no less than 326 balloons in a mass take-off today, to establish a new world record for the most balloons to do so at one time. Thanks to Eugenie L. for e-mailing these pictures to me (click them for a larger view), and also the link to the video.
The video below was taken by one of the participants from the basket of their balloon at the start of the mass lift-off. This is a high-definition video, so it may be a little slower than usual to load, but the picture quality's worth it.
Beautiful! I'd have loved to have been there, to see it in person.