We find that employment losses [in the US manufacturing sector] . . . are associated with relative increases in U.S. imports from China, the number of U.S. firms importing from China, the number of Chinese firms exporting to the United States, and the number of U.S.-China importer-exporter pairs. P. 20.
That is from this new paper (December 2012) by Peter & Schott.
Who benefits from these large changes? One instance could be people living in countries like Haiti, where they are buying a lot of relatively cheap (but OK quality) Chinese-made products, such as motorcycles.