Embassy Row, that weather vane of how United States foreign policy playing abroad, cast its vote last night for U.S. secretary of state. Of those ambassadors present and accounted for at the Japanese Embassy, Sen. Edmund S. Muskie (D-Maine) won hands down.

"A good man," said the Soviet Ambassador Anatoliy F. Dobrynin, declining to go into detail as he and his wife pressed through a crowd of several hundred guests invited by Japanese Ambassador and Mrs. Yoshio Okawara to celebrate Emperor Hirohito's 79th birthday.

"An excellent appointment," said the Ambassador Tabarak Husain of Bangladesh, "one that will greatly reinforce the administration's worldwide efforts to mobilize support for a peaceful solution of the Iranian crisis."

"Canadians would be delighted," said Ambassador Peter M. Towe of Canada, noting that the U.S. ambassador in Ottawa is also from Maine. "Senator Muskie knows a lot about Canada-U.S. problems. I've known him for many years -- most Canadians have known him for many years."

The accolades for Muskie, in fact, were almost hip-deep as diplomats and Washington's official and unofficial foreign-affairs community alike reacted to President Carter's announcement that he was nominating the senator to succeed Cyrus Vance.

"Quite a man," said J. William Fulbright, who was chairman of the Senate Foreign Relations Committee when he was a senator from Arkansas and Muskie was on the committee with him.

And how did Fulbright think Muskie would hit it off with national security adviser Zbigniew Brzezinski?

"Why, he'll get along just fine," said Fullbright, whose wife, Betty standing beside him, suddenly burst into laughter. "now you keep your mouth shut," Fullbright scolded her, though not too seriously, and she walked away-- laughing with her mouth shut.

Sen. Daniel K. Inouye (D-Hawaii), one of the few members of Congress who made it to the party, said he's known Muskie more than 20 years "and any man who can stand up to him must be exceptional. I've never known Ed Muskie to play second fiddle."

A couple of former under secretaries of state -- U. Alexis Johnson and Joseph Sisco -- joined the approving chorus.

"Very fortunate for the president that he's willing to serve in the job." said Johnson, under secretary for legal affairs from 1969 to 1973.

"A centrist in view, with a combination of executive and legislative experience and the stature to speak with a firm voice," said Sisco, under secretary for political affairs under Henry Kissinger."

If there were diplomats in the crowd who were opposed to Muskie, being diplomats, they couched their comments behind sufficiently vague assessments.

Pakistan's Muhammad Khan said he hasn't been in Washington long enough to know Muskie personally, "but I'm guided by what I hear, and the general response is favorable here."

Saudi Arabis's Ambassador Faisal Alhegelan said that he wasn't really surprised, but that on the other hand Muskie was "an outsider -- nobody was mentioning his name" in speculation after Vance's resignation.

Morocco's Ambassador Ali Bengelloun, with antennae better than most, said he wasn't at all surprised. "A few months ago when Vance was talking about leaving, somebody told me that the next secretary would be somebody from the Senate."

What struck Arthur Dornheim, executive director of the Japan-America Society, about the turn of events was something he and his wife pondered as they stood in the lobby of the Japanese Embassy watching little knots of people talking.

"Has anybody commented on the irony of two Polish Catholics overseeing our foreign affairs?" he asked.