A lot of fuss about not quite the right thing. The real problem is the caloric density and, frequently, nutritional paucity of the highly processed foods to which HFCS is added during food processing.
HFCS is made by breaking down corn into its chemical components and altering the ratio of glucose to fructose. (Fructose is naturally much sweeter.) Biochemically, sugar and HFCS are virtually identical, and HFCS has the same number of calories per gram as table sugar. It's cheaper to produce than sugar, which is why so many food manufacturers use it in everything from breads to beverages.
BOTTOM LINEFocus on calories consumed and the nutritional value of what you eat. Eat more whole foods, and you'll avoid HFCS altogether.