What is America's most prominent Muslim advocacy group hiding? The Council on American-Islamic Relations is delinquent in filing its tax returns by nearly two years, the IRS has confirmed, raising new suspicions the embattled nonprofit group is concealing from the American public details about its already shadowy financial activities. Washington-based CAIR, which receives revenue from Saudi Arabia and other Arab states, is required by federal law to file its tax returns annually with the IRS to maintain its tax-exempt status. However, it still has not filed its 2007 returns, according to the IRS. Its 2008 tax filing is also late....