Passionfruit ("maracuj") seems pretty hard to come by in the U.S. One piece of passionfruit could cost you as much as $5, which makes for a very expensive drink at the bar. If you can get real passionfruit juice or puree, the experience is close enough but it's certainly not the same.
Here's a basic demonstration of how to make a passionfruit caipirinha, using juice:
About two minutes into this video below, you'll find Sagatiba's recipe for the Empire Cooler (also referred to as the Empire Collins), made especially for the Empire Hotel in New York. This incorporates passionfruit juice, with half of the fruit itself used as a garnish.
All that said, there's nothing quite like a real passionfruit drink, though.