Stop the presses. He covered the national political conventions, and now Ron Reagan, the president's son, plans to cover next week's U.S.-Soviet summit in Geneva for Playboy magazine. Swiss authorities have accepted the younger Reagan's request for accreditation as a journalist to cover the meetings Tuesday and Wednesday between his father and Soviet leader Mikhail S. Gorbachev. Dancing Dynasties

Final notes on the royal long goodbye: Down in sunny Palm Beach, Prince Charles danced with the va-va-voom star of another "Dynasty," Joan Collins, and the British press was all atwitter. In her slinky low-cut gown, several guests speculated she was trying to upstage the princess. One British newspaperman had even suggested on the plane to Palm Beach earlier in the day that Collins had arranged to get married for the fourth time last week to compete with Diana. If she did, she failed to get much attention. Yesterday morning, however, when a reporter asked Collins about attempting to upstage the princess of Wales, Collins said, "Ludicrous, ludicrous, ludicrous, absolutely ludicrous." She probably could have answered more definitively . . .

Newsweek magazine Senior Editor Mel Elfin walked around the elegant ballroom of the Breakers Hotel in Palm Beach Tuesday night at the glittery dinner hosted by industrialist Armand Hammer and attended by a passel of the rich and the royal couple. As he looked at the spangled, bejeweled women in the room, he grumbled, "if you added up the cost of the gowns here it would equal the gross national product of three small African countries." . . .

Merv Griffin and Eva Gabor flew direct from the party to Washington yesterday to attend this weekend's running of the International at Laurel. They checked into the Vista International Hotel, in separate rooms. Griffin, who is beginning to resemble a fireplug, is on a special fruit diet, which he washes down with Tattinger Champagne. End Notes

It was almost the first thing Edmonton Oiler great Wayne Gretzky wanted to know when he got off the airplane Monday night. "How do you get to Joe Theismann's restaurant?" WTOP reporter Joe Connolly asked Gretzky what he would advise Redskins quarterback Theismann, who hasn't been having a good year. Gretzky said if Theismann asked him he would say, "It's a long way from over yet." In speaking about Theismann, Gretzky said that the quarterback is so good that "every single team is up for him." Without knowing it Gretzky may have predicted his own team's fate the following night when the Washington Capitals upset the Stanley Cup champion Oilers . . .

Sen. Lawton Chiles was admitted to Bethesda Naval Hospital yesterday for tests due to high blood pressure . . . Sen. Jay Rockefeller attended a birthday party Monday night for Sen. Edward Zorinsky, who was recently released from the hospital, where he was treated for chest pains . . .

The organizers of next week's Capital Press Club Award dinner sent out an invitation that announces singer Lena Horne as the invited keynote speaker. However, Horne's spokesman, Sherman Sneed, said the singer had previous commitments and cannot be there . . .

Stranger things have happened. Workers at a 3M company plant that is scheduled to be closed, throwing 450 out of work, have appealed to singer Bruce Springsteen to save them. The audio-tape plant is in Freehold, N.J., Springsteen's home town. The rock singer once wrote "My Hometown," a hit song about a textile plant closing down. The employes also have asked country singer Willie Nelson to help. Springsteen is reportedly seriously considering the request . . .

Three-time Academy Award winning director Haskell Wexler was in town last night for a special showing of his new Lucasfilm, "Latino," a movie that promises to be explosive because it is highly critical of U.S. policy on Nicaragua. It's the fictional story of an American Green Beret sent to train contras in Honduras who falls in love with a Nicaraguan woman and begins to question his involvement in the war. After the viewing at the Key Theatre in Georgetown, Wexler and his niece, Daryl "Splash" Hannah, who is not involved in the movie, attended a small reception at nearby Champions bar.