Time Warner is SD has MLB TV on digital cable channel 489 in standard and 789 on HD.

http://www.latimes.com/sports/la-sp-mlbtv1-2009jan01,0,5859021.story

The NFL and NBA have full-time television networks up and running, and starting at 3 p.m. PST today Major League Baseball will follow.

ESPN, the most-watched sports cable station, reaches 98 million homes. The MLB Network, in part to forestall the access problems of the NFL Network, has made part-owners of several cable companies, including Time Warner, DirecTV and Cox, MLB Network President Tony Petitti said.