I watch nutrition labels and often find them infuriating. They often don't give the information I'm looking for (potassium, for instance, is seldom mentioned) or they give information but I have to do some arithmetic to figure out what I want to know. The serving size is often confusing, just for an example.
The US FDA has just announced major changes in its nutrition information label. Potassium will be included, and other changes seem to be improvements as well:
http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm387418.htm