Using a large chef's knife, cut the melon in half. With a wooden spoon, remove the melon seeds from each half and discard. Cut each melon half into eight equal pieces. With a paring knife, remove the rind from each slice. Set aside.
Hold the mango upright on a cutting surface. Using a chef's knife, cut away the flesh on both sides of the pit. Carefully peel each mango half. Cut each half widthwise into eight equal pieces. Set aside.
Using a cool, damp cloth, gently wipe the fuzz away from each peach. With a paring knife, cut each peach in half lengthwise, and remove the pit. Cut each peach half into four equal slices. Set aside.
Divide the fruits equally among four plates. Season with salt. Top each plate with two pieces of prosciutto, covering the fruit. Garnish with a sprig of cilantro and a wedge of lime. Serve immediately.
(c)2004 Martha Stewart Living Omnimedia, Inc. All Rights Reserved.