I've posted plenty of times on RetailWire as a supporter of NYC's initiative to get calorie counts on the menus at chain restaurants. I think it's very misleading to consumers to use terms like "low fat" when hidden behind that sign is something that slugs 1,000 calories or more. So, sure, some restaurants post calorie counts online or in little brochures that sometimes are easy to find or available in the store (and sometimes not), and their argument has been that because they do make the information available, they should not have to put it on menu boards.
The problem with online information is that it's not accessible for when you're making a product selection decision. A lot of online calorie calculators that I've seen restaurant chains put out are not mobile phone friendly at all - they require you to "build a meal" and then tell you, once you've configured multiple options through multiple screens - you get a result. Taco Bell's is a good example.
Here's where it gets interesting. Contrast that with efforts by companies like Staples, who has debated publishing consumer-generated product reviews at the shelf - and the huge number of questions doing something like that generates. Which review do you pick? Is it misleading if you publish a highly favorable review when overall the reviews tended toward the negative? What do you do with a product that received mostly negative reviews? And on and on.
Mobile phones do change the game a bit - providing price and sometimes availability through a mobile phone search is rapidly becoming ante. Reviews (or at least summarizations of reviews) will likely be next, if not additional spec or detailed information - like nutrition info, in the case of restaurants. There are calorie-counting sites out there that will help - like My Calorie Counter - but it's still interface-intensive to compare multiple products against one another.
The ultimate challenge is balancing what you can provide to consumers against what different customers want as part of the experience. MSNBC calls reaction to the calorie information "sticker shock" of a sort, and quotes a NYC health official who is perfectly happy with that result, while meanwhile a restaurant patron wants to switch menus with her friend who received an old one that doesn't have the calorie counts - because she wants to be kept in the dark. It all just makes me think that dynamic displays are an inevitability (granted, once the cost to implement reaches something that retailers can afford to invest in) - so that consumers can taylor what they see, not just online, but even when they're looking at the shelf.
And, for the record, given that California is looking into even stricter standards, and that retailers already have to accomodate New York's specific rules, I believe it will be a short amount of time before we see calorie labeling spread nationwide.