TALK WARS

Watch out, Joan--Johnny’s lined up reticent Sean Penn for a rare talk show appearance when “The Late Show Starring Joan Rivers” (11 p.m.-midnight, KTTV Channel 11) debuts against “The Tonight Show” Oct. 9. Carson’s other big gun that night: Richard Pryor.

Rivers counters with David Lee Roth, Elton John and Pee-wee Herman. Meanwhile, David Brenner’s “Night-life” (11-11:30 p.m., KCOP Channel 13) has booked Yoko Ono.

A spokesman for the Rivers show had “no comment” on the booking wars, except a very predictable “There’s room enough for everyone.”

We also wondered why Sean’s willing to gab on camera. All he’d offer (through his rep) was terse: “Listen, it’s very simple. They asked me to appear on the show and I accepted.”