The FDA recently issued its final decision on trans fat - revoking its Generally Recognized as Safe status (GRAS) and therefore effectively banning them from the food supply. The food industry has been given three years to phase out trans fats completely from the food system. Until then, trans fats are easy to spot in packaged foods - just look for "partially hydrogenated oil" in the ingredients list. Trans fats can still be found in products like cake frostings, pancake mixes, taco shells, microwave popcorn, margarine, and baked goods such as hamburger buns and tortillas.
Trans fat raises your LDL (the "bad") cholesterol and lowers your HDL (the "good") cholesterol, increasing your risk for heart disease.
In 2003, the FDA required trans fat to be present on the nutrition facts label as of January 1, 2006. This prompted many companies to begin removing trans fat from their products.
In 2007, New York City put into effect a regulation that restricted trans fat use in all New York City food service establishments.
For more information on trans fats, visit the FDA, the American Heart Association, and the Center for Science in the Pubic Interest (CSPI).
And for additional reading on food and public policy:
Helena Bottemiller Evich for Politico