Couple things we know. Childhood obesity is basically a national health crisis. Sugar cereals, as we called them when I was a kid, are not good for us, despite being delicious and despite marketers' best efforts to have us think otherwise. Now, thanks to a leaked Yale University report, we can add one more factoid to he mix: Preschoolers are bombarded with cereal ads an average of 642 a year.Now, we're not talking about ads kids may incidentally happen upon. We're talking about targeted and wily marketing campaigns geared directly and solely to kids, like this weird website where kids can play around in a silly rabbit's phantasmagoric world, in which the grass is sprinkled in-what else?-Trix.As for the titular question-it's something Eric Schlosser proposes in the epilogue to Fast Food Nation. He says it plainly: "Congress should ban advertising that preys upon children." Well, a couple of years ago, the business pledged to begin policing itself (which always works out great, right?), and that has resulted in the marketing of sugar-filled cereals as solid nutritional choices because of their low calorie count or because there are "grains" in each serving.It's been a bad week for the cereal business, but next week will probably be worse, when crappy cereals are fingered as public enemy number one at the national obesity conference in Washington.So what do you think? Should Congress step in? Should people vote with their wallets instead? Is it fair game in a free market economy?