SAN FRANCISCO - A federal judge in San Francisco blocked the Bush administration today from imposing a rule that would require employers to fire workers identified as illegal immigrants in government records or face possible prosecution. U.S. District Judge Maxine Chesney granted a nationwide temporary restraining order sought by the AFL-CIO and affiliated unions to keep the government from sending letters to employers demanding that they clear up workers' citizenship status. The order will be in effect until Oct. 1, when another federal judge will consider whether to grant an injunction that would block the rules until a trial on...