Two months ago, most U.S. retailers were expecting a slight increase in sales in the neighborhood of 2%. But as Thanksgiving neared here in the States, pundits suddenly were projecting bigger gains and optimism grew that Holiday 2010 would prove bountiful for everyone. But now, all that may be wishful thinking, according to early results. U.S. retailers posted mixed December same-store sales results Thursday as the holiday season in many cases failed to live up to retailers’ highest e...