They are looking at standardizing the sizes.  So 1 can or 591 ml bottle of Pop will be 1 serving.  They are also looking at standards across a category - so all cereals would have the same serving size.

I have been following the food labeling discussions closely because I am in the food industry - I am not effected by the current discussions as I don't manufacture for retail products but for Food Service.

What I find interesting is that we have more of an Obesity issue now than when I was a kid in the 80's when the only information that had to be on the label was the ingredients.  It has to be more than a lack of information - either people don't understand or they don't care.