Not quite the publishing event of the decade, perhaps, but certainly Paper Jacks Ltd.'s newest paperback, "Gorbachev: Mandate for Peace," rated some extraordinary measures. Since nothing's too good for the boss, Soviet Ambassador Yuri V. Dubinin called a press conference.

Even so, Dubinin seemed a bit uncertain. Slipping into the Soviet Embassy's gilt and oak-paneled second-floor room, where three dozen journalists stood awaiting him Friday (there were no chairs), Dubinin gently tapped one reporter on the shoulder to ask: "What we will do now -- press conference or just a presentation? What formula would you like?"

Not surprisingly, the consensus was a press conference, and if it did not exactly make history in news content, it probably did in length. For more than an hour the silver-haired Dubinin held forth on everything from arms control and Afghanistan to Central America and Soviet Jewry -- and for the record, the boss' book.

"The better we will know each other, the better it will be for our relations," Dubinin said of the book, which is a selection of writings from three Mikhail Gorbachev books that Richardson and Steirman of New York has published in hardback in as many years.

The book is the latest of Soviet efforts to flack their peace message before this fall's Reagan-Gorbachev summit. It didn't take a public relations expert to figure out that timing was everything in distributing the initial printing of 200,000 copies to supermarkets, drugstores and bookshops around the country.

"We felt we had to have it in the stores by mid-October in order for Americans to see it and know about it. We were always working under the assumption that the secretary general was coming over," said Tony Seidl, the Paper Jacks publisher who paid $10,000 for the paperback rights.

Seidl said Paper Jacks has no plans to promote the Gorbachev tome. "We've got a great promotion going -- Gorbachev's coming over here."

Royalties will go to Gorbachev's favorite "charity" -- the Soviet cultural organization, which Raisa Gorbachev so ardently supports.

Stewart Richardson, president of Richardson and Steirman, got his first Gorbachev book to publish when he simply wrote the Soviets a letter asking for a book on foreign policy. He said he met with Gorbachev for an hour in August and found him "very smart, not doctrinaire."

Richardson said he is now working to publish Raisa Gorbachev.

"It's going to cost a lot of money, but there is a chance," he said.

While Mikhail Gorbachev is getting ready to charm Americans, his ambassador has already charmed social Washington. Hosting a gala reception last week for the Washington International Horse Show crowd, Ambassador Dubinin offered glasnost over caviar.

He was everywhere, chatting up horse show officers such as Wyatt A. Stewart III, president, and Marine Commandant P.X. Kelley. Doing her part was Dubinin's wife Liana, chic in an off-white cocktail dress and the ubiquitous amber beads.

The show's executive director, Eve Lloyd Thompson, got a preview in August when, in search of a horse act for the 1988 show, she went to the Soviet Union as a guest of the government. What she saw was a superb act of trick horses and stunt riders, some of whom appeared in the film "Peter the Great." If Thompson was enthusiastic, the Soviets were more so, promising to donate the act to next year's show if they can arrange commercial bookings while it's here.

In the Soviet Union, Thompson was wined and dined at a Black Sea resort whose resemblance to the French Riviera so struck her that she told a Soviet official: "You must be inundated with American tourists."

His reply: "You are the first American I have ever met."

The conduit in arranging Thompson's visit was embassy counselor Valeri Sorokin, the first Soviet rider in anybody's memory to be featured in the show's celebrity rider class. The show opens Sunday and continues through Nov. 1 at Capital Centre.

If the White House seems to lay claim to the poinsettia plant every Christmas season, it's probably with good reason. John Quincy Adams -- America's sixth president and also its best remembered for a love of gardening -- was partly responsible for the plant's introduction into the United States. Joel Poinsett, his minister to Mexico, brought the red bloom back from its native Mexico because he knew of Adams' interest in flowers and trees. Poinsett ensured his own immortality by naming the plant for himself.

The White House Historical Association is commemorating Adams this year with its 1987 White House Christmas ornament, which will hang on the mansion's tree in the Blue Room. Done in a 24-karat gold finish with red and green enamel, the ornament depicts the North Portico's mahogany double doors festooned with evergreen Christmas wreaths and flanked by poinsettias. The ornament may be purchased by mail for $9.75, including postage and handling, from the White House Historical Association, Dept. 3030, Washington, D.C. 20042. The permanent White House collection of historical furnishings and art works benefits from the ornament sale proceeds.

Christmas is still 67 days off, but Nancy Reagan says she and President Reagan already know what they are giving each other for the occasion: Framed copies of their medical diagrams, as seen in the media, to set on their nightstands.

Elaine Crispen, Mrs. Reagan's press secretary, said the first lady was in great spirits on Sunday, the day after her breast cancer surgery at Bethesda Naval Hospital, "laughing like crazy" over the gift idea.

Mrs. Reagan was less than amused last winter when the media showed diagrams of the president's prostate surgery. In 1985, she also deplored drawings of Reagan's colon cancer operation.

This time, however, Crispen said Mrs. Reagan has been uncritical of the television coverage of her own surgery. Crispen called the coverage "very nice, very straightforward, handled beautifully."

Pavarotti, Baryshnikov, Falwell, Fairbanks, Keach, Mubarak, Gandhi, Seaga, Ford, Rockefeller and on and on goes the list of well-wishers sending cables, cards and messages to Mrs. Reagan.

Longtime friend Mary Jane Wick dropped in to visit yesterday afternoon, joined shortly thereafter by Crispen. The two found a talkative first lady who didn't seem to want to stop.

"After an hour and 15 minutes, I was beginning to worry that I was staying too long," Crispen said.

Crispen said Mrs. Reagan exercised her left arm to limber it up after the surgery removing the lymph nodes under her armpit. She also primped for her steak dinner with the president.

On her bedside table was a copy of "Life and Death in Shanghai," whose author, Nien Cheng, whom the Reagans invited to last week's state dinner for Salvadoran President Jose Napoleon Duarte, also sent well wishes.

Flowers came from all over, including from former president Gerald Ford and Betty Ford, who also had surgery for breast cancer. Kathy Osborne, the president's personal secretary, sent Mrs. Reagan a stuffed copy of First Dog Rex.

On the family front, the first lady received calls from daughter Patti Davis and stepdaughter Maureen Reagan, but as of yesterday hadn't yet talked to son Ron Reagan and stepson Michael Reagan. Ron, who is in Moscow with the ABC-TV "Good Morning America" cast, learned of his mother's surgery from his wife Doria, who reached him there by telephone. And it fell to the first lady's other daughter-in-law, Colleen Reagan, to call the first lady on behalf of her husband Michael, who himself underwent surgery last week for the removal of polyps on his vocal cords. His doctors advised him to keep quiet for awhile.