The trial of hedge-fund billionaire Raj Rajaratnam has riveted the financial world and shined a light on the phenomenal success and insularity of the Indians, Pakistanis, Bengalis, and Sri Lankans flooding the American financial sector, writes Gary Weiss. Following every financial collapse, a cast of Wall Street bad guys invariably parades through the dock, from Depression-era thief Richard Whitney to junk-bond king Michael Milken to Ponzi schemer Bernie Madoff—media-saturated jaunts down the Via Dolorosa calculated to reassure the public that the financial markets are being policed, even though they’re not. This week, it’s the somber, bespectacled, self-made billionaire Raj Rajaratnam...