Fred R. Conrad/The New York Times, 2004Dan Rather might work for the high-definition channel HDNet. The 74-year-old man with the Mets cap pulled far down on his forehead slid into a booth at a diner on the Upper East Side of Manhattan and ordered a glass of milk without so much as turning a head — so quietly, in fact, that it was hard to believe it was Dan Rather. In place of the swagger that had served him so well throughout his 44-year career at CBS News was an obvious sadness that his tenure at the network was...