There are two basic methods for eating with a knife and fork. The "American" involves having your fork in your left and your knife in your right when cutting your food, then putting the knife down and switching your fork to your right hand to eat, tines facing upwards. (If you're right-handed, that is.) With the "European" method, the fork remains in the left hand and the knife helps coax your food onto your fork. The tines remain facing downwards.
Lately I've noticed that more Americans are adopting the European style, perhaps to appear more well-traveled and sophisticated? Or maybe it's because the European method is simpler and more efficient?
More interesting facts about European vs American eating styles:
According to some etiquette books, the American style came to the States with the British colonists and took hold here, while the European method is a somewhat more recent change.
The European style is also referred to as "hidden handle" because the knife and fork are held in such a way that the handles are tucked into the palm and held by the thumb and forefinger.
The American style is also referred to as the "zig-zag method" where the fork is held like a spoon and indeed sometimes used like a spoon to scoop rather than spear food.
According to Wikipedia, American spies were exposed in at least two American films by using the wrong fork technique: O.S.S. (1946) and The Big Red One (1980).