Combine pineapple juice, sugar, 1 cup water, and peppercorns in a small saucepan. Set over high heat, and bring to a boil. Reduce heat to a simmer, and cook until flavorful, about 30 minutes. Remove pan from heat, and pass liquid through a sieve set over a heatproof bowl. Discard solids.
Have ready an ice bath. Add the pineapple, mango, and kiwi to the poaching liquid, and let stand 15 minutes. Set the bowl into the ice bath; chill, stirring occasionally.
When ready to serve, divide sorbet, chilled fruit, and remaining poaching liquid among four dessert plates.