Summer must finally be over. From the tireless Democratic pols hoping against hope, to international czars celebrating yet other end to a horrible ordeal, Washington last night was once again dancing and networking. Irving Kristol beamed, crowds sang Lena Horne's praises and Yitzhak Shamir looked simply relieved. It was a night like many others, charged with energy and expectation, and it left little doubt: The social season must be here. Neos Anew

"I'm tired," George Shultz said. "It's bad enough without having the terrorist thing."

"I don't know what the solution is," Irving Kristol commiserated. "We'll assist you in any way we can. Maybe they'll just go away. Can I get you a drink?"

At last night's coming-out party for The National Interest, Kristol's heavyweight neoconservative foreign-policy quarterly -- copies of which were dense-packed on a table to the side -- the crowd was heavyweight indeed. Happily, the floor in the Sheraton Carlton's Crystal Room held up just fine.

"I don't want to be interviewed," said the secretary of state, holding up a hand. Then, smiling thinly at the end of yet another hostage crisis, Shultz turned away to make small talk with the likes of former Australian Prime Minister Malcolm Fraser, CIA Director William Casey, White House Communications Director Patrick Buchanan, AFL-CIO President Lane Kirkland, Commentary editor Norman Podhoretz and a host of other eminences.

"I wrote a light piece, the most frivolous article in the magazine," National Interest contributor Edward Luttwak told Shultz brightly. On inspection it turned out to be an essay on Soviet ruthlessness and intelligence gathering.

"This is a distinguished group of people whose ideas are taken seriously," said Secretary of Education William Bennett.

As Fraser mulled over the possibilities of counterterrorist retaliation in one corner of the room, Ernest Lefever, president of the Ethics and Public Policy Center, buttonholed the CIA director on the subject of "liberating Afghanistan" in another. Kenneth Adelman, director of the Arms Control and Disarmament Agency, talked Geneva, and Norman Podhoretz foraged for food. "The pineapple is terrific and so is this; I think it's some kind of beef teriyaki," he said.

Surveying the scene, the diminutive Kristol looked like a happy man. The spiritual leader of neoconservatives everywhere -- and definer of neoconservative as "a liberal mugged by reality" -- he is publisher of The Public Interest as well as The National Interest. What's next, The Special Interest?

"My son suggested we have The Private Interest," Kristol said, "and then maybe after that, The Self Interest."

Editor Owen Harries, a Welshman turned Australian, said, "If we were having this in Australia, there would be a very large keg of beer, lots of flies, a barbee going, and I don't think there'd be blood on the floor but it wouldn't be impossible."

Kristol didn't seem to be spoiling for a fight with Sen. Daniel Patrick Moynihan, a sometime foe. He got him a drink. While Kristol is neoconservative, Moynihan has occasionally been called neoliberal, leading to label confusion.

"A neoliberal is a kind of liberal and a neoconserative is a kind of conservative," Kristol patiently explained.

But Midge Decter, spouse of Podhoretz and head of the Committee for the Free World, elaborated. "Pat Moynihan is not a neoliberal," she insisted. "He's a former neoconservative who has become a liberal. I don't see any neoliberals here. A neoliberal is a neoconservative who imagines that he can get away without taking responsibility of his positions."

Lane Kirkland stood in a corner and grinned. "I knew a lot of these people when they were still good Democrats," he said. A Sense of Relief

Israeli Foreign Minister Yitzhak Shamir welcomed official Washington to the Israeli Embassy last night, at the end of what had been a very long day in diplomatic circles.

"It's good that [the crisis] came to an end," said Shamir, whose country was the target of demands by the Palestinian terrorists who held more than 500 hostages on a cruise ship off the coast of Egypt. "But I'm not happy that the terrorists escaped punishment and trial . . . To cause agony to innocent people who are not involved in the Mideast crisis -- it is inexcusable. They have thrown a helpless 69-year-old man overboard. How can these people be let free?"

"I don't know to what extent one can say it's over," agreed Israeli Ambassador Meir Rosenne, who used the opportunity to get in a shot at Egypt. "One should question the country involved for not taking steps to prosecute. If they have in fact all the terrorists been let go, it is a sad situation."

About 300 guests, many of them business leaders and politicos from the Jewish community, filed into the embassy to greet Shamir, who is here on a two-day official trip. Earlier in the day, he met with Secretary of State George Shultz, and tomorrow he meets with members of Congress.

Other guests were Sen. Alan Cranston (D-Calif.), Sen. Rudy Boschwitz (IR-Minn.) and Interior Secretary Donald Hodel.

"Are you enjoying your new job?" Shamir asked Hodel.

"It's a very exciting job," Hodel said. "But everyone is picking on me. I'm beginning to know now how Israel must feel." Everyone laughed knowingly. The Horne of Plenty

The sleek figure in floating gray dress and red shoes whirled by with a grace unusual for even the most sophisticated Washington party crowd.

"I'm working the party!" said a smiling Lena Horne as she was whisked off to meet yet another guest at last night's reception in her honor. For two hours she was introduced to new faces, kissed by old ones and beamed upon by all the throng gathered at the Ritz-Carlton to welcome Horne, who has just moved to Washington.

"I really liked the place," she said between whirls. "My uncle used to work here and I visited all the time when I was growing up. He worked for Roosevelt; he was one of the men on what was called the Roosevelt black cabinet. I think his picture's in the Smithsonian.

"The thing is, I've been rushing around so for a while -- all my life -- and New York got too much for me. Here I can come back, settle down and see a tree."

Former Urban League head and longtime Horne friend Vernon Jordan and former president of the American Cancer Society LaSalle Leffall stood with Horne in a receiving line that kept dissolving as the singer was swept off by eager friends.

"We thought we'd have a party to introduce her to the neighborhood," said Jordan.

The neighborhood consisted of: politicians past and present, like former congressman James Symington and Rep. Charles Rangel (D-N.Y.); arty people like AFI director George Stevens and printmaker Lou Stovall; media-types Carl Rowan and Wall Street Journal Bureau Chief Al Hunt, and about 200 others.

"The problem, of course, was finding a date," said Ruth Leffall, "because everyone's so busy. She Horne just got in from California, Vernon leaves for China in the morning, we leave for Chicago for 10 days -- you know the story."

Another traveler was Joan Kennedy, down from Boston and surrounded by cries of "Welcome back!" and a solicitous Steve Martindale, the lawyer and friend who brought her to the party.

After one round of cheek-kissing was completed, Kennedy said she was in Washington to attend a birthday party Tuesday night for Jim English, former pastor of Holy Trinity Church in Georgetown, but that she also knew Horne from New York.

"I've seen all my old pals tonight," she said, Martindale standing protectively by her side.

Asked how she thought Washington would respond to its newest celebrity resident, she said, "I don't know, I live in Boston. I'm very happy in Boston."

And all the while, Horne was responding to a stream of invitations to lunch and dinner, her daughter Gail Buckley was always near for those moments when Horne turned to her, laughing, and asked, "What's my phone number, darling?"