WORTH NOTING ON TV

* THURSDAY

Baseball playoff (CBS, 8 p.m. to conclusion, E.T.): The Atlanta Braves face the Phillies at Philadelphia's Veterans Stadium in Game 2 of the National League Championship Series. The pennant goes to the winner of four games. * FRIDAY

Radioactive TV (Comedy Central , 8 p.m. to midnight): Prominent radio personalities make forays into TV every once in a while, usually without enduring results. Jean Shepherd, whose funny and sometimes haunting monologues turned radio storytelling into an art form, tried TV a few times. Garrison Keillor of ``A Prairie Home Companion'' brings his beguiling style to the tube from time to time. And if you go back far enough, some of radio's biggest names (Jack Benny, for instance) became TV's biggest names.

Now here's another attempt to get radio types on the screen, and a cable channel like Comedy Central is probably the place to do it. These days, radiowaves are often dominated by talk-show hosts, some of them a real grass-roots political force, others who are funny. It's the latter who have been recruited as deejays to usher viewers through Comedy Central's regularly scheduled Friday evening shows, like ``Stand-Up, Stand-Up'' and ``Almost Live.'' The fugitives from radio will do comedy routines, introduce shows, lead into and out of commercials, and generally put on display talents once only heard. * SATURDAY

National Press Club

(C-Span, 6-7 p.m., E.T.): The speaker is Manfred Woerner, secretary general of the North Atlantic Treaty Organization.

A Life in the Theatre

(TNT, 8-10 p.m.): Prize winners on both sides of the camera join forces in this new production of the 1977 David Mamet drama about two actors and their professional and personal lives backstage. Jack Lemmon portrays the older player, whose career is on the decline. Matthew Broderick plays a rising young actor. On stage and in the dressing room, their relationship is traced during a season of repertory plays.

Please check local listings for these programs.