NEW YORK -- CBS News on Thursday fired the executive producer of Katie Couric's struggling "CBS Evening News" broadcast and appointed former CNN and MSNBC president Rick Kaplan to the job. Kaplan replaces Rome Hartman, who had position since before Couric began at CBS last September, said Sean McManus, CBS News president. The newscast has been a distant third in the ratings behind ABC and NBC. During last month's pivotal ratings "sweeps" period, Couric's average of 7.6 million viewers was 6 percent down from what Bob Schieffer recorded in February 2006. More troubling to many who watched it was the...