One of the things Finland did was require a label on foods that were high in sodium. If you didn't meet a certain threshold you had a warning label put on your product that this food is high in sodium. Government can do a variety of things, both in voluntary education but also in regulation.
I think Andrew's point is a very good one: it does create a level playing field. It rewards those companies that are already making a difference and it takes the laggards, who simply can't be bothered, and pulls them in. We've seen the same thing with trans fats. There are companies that have removed all the trans fats from their products, and companies that haven't removed the trans fats at all or very little. It creates a level playing field, not only for the food industry but also for Canadians.