David Letterman had been expected to beat Jay Leno in the ratings for the second night in a row Tuesday following a plea deal by former CBS-TV news producer Joe Halderman to plead guilty to charges that he attempted to blackmail Letterman. (Halderman received a six-month jail sentence, four and a half years probation and 1,000 hours of community service.) And in fact, Nielsen overnight results from the top 25 markets did give Letterman a slight edge. However, when the so-called fast national ratings were released on Wednesday, Leno had taken a slightly lead with 4.216 million viewers to Letterman's 3.973 million. The numbers were so close that there were considered statistically inconclusive. Leno also wound up on top by two-tenths of a rating point among adults 18-49 and just one-tenth of a rating point among adults 25-54. In fact, Letterman had little to say about the outcome of the blackmail case. He did not mention the result except to say that "the matter was resolved today." He then thanked -- by name -- members of the New York District Attorney's office who had worked on the case.