The New York Times has an article today saying:
Childhood obesity, rising for more than two decades, appears to have hit a plateau, a potentially significant milestone in the battle against excessive weight gain among children.
It is not clear if the lull in childhood weight gain is permanent or even if it is the result of public anti-obesity efforts to limit junk food and increase physical activity in schools. Doctors noted that even if the trend held up, 32 percent of American schoolchildren remained overweight or obese, representing an entire generation that will be saddled with weight-related health problems as it ages.
Here's a more understandable infographic I came across somewhere awhile back.