WASHINGTON -- Already short on jobs, some American high-tech workers are mobilizing against a growing threat that they will be replaced by foreign workers arriving on a once-obscure visa.Across the country, U.S. workers who once protested that H-1b visa holders were displacing them are now focusing on the growing use of the less-restrictive L-1 visa to bring bargain-priced foreign labor to major corporations.Even in the sinking U.S. job market after the high-tech bubble went bust, the number of L-1 visas has risen and is now estimated at 325,000 temporary workers, who are allowed to stay between five and seven years.The...