Included in the 1,990-page health care reform bill introduced by Speaker of the House Nancy Pelosi was an outline for general nutrient-labeling requirements for restaurants and retail outlets with 20 or more outlets.

Affected restaurants would be required to prominently post calorie counts on menus and menu boards as well as calories per serving for items in salad bars and self-serve set-ups. They would also be required to post a reminder about the recommended daily caloric intake to help put all those numbers in context as well as let customers know that more nutritional information on their menu items is available upon request.
Vending machines would also be subject to calorie-posting rules.

Read more here.
Personally, I don’t see much harm in informing the public—I think that this information can help people make good choices for themselves. Of course, it makes it easier for obsessors to obsess, but a lot of people in that boat look up calorie counts online anyway. I don’t think it’s necessarily the cure to all our country’s diet-related health problems, but I usually am in favor of educating people.
For some, this could have a positive impact, and for others, it could have no impact. You wouldn’t really be able to tell the overall effect for a while after substantial research, but I’m interested to find out if it works.