Singer Michael Jackson's career seems to be red-hot again. The Japanese leg of his worldwide concert tour was one long sellout, his new song "Bad" is the No. 1 single in the country, and the results of his new multimillion-dollar Pepsi commercial deal are about to be released on national television. One 90-second spot called "Concert" will debut Friday on MTV, and a 60-second spot titled "Backstage" will air on the same channel Saturday. "Backstage" is about a young fan meeting the star in his dressing room. A 60-second version of the "Concert" commercial will begin appearing on network television Sunday.

This series of commercials, the second Jackson has done with Pepsi, is part of a contract deal he signed last May for which he is reportedly being paid $10 million. Pepsi is also sponsoring Jackson's worldwide tour. The next phase of the ad campaign, which is expected to be ready early next year, will consist of four-part episodes that a Pepsi spokesman said are "the most elaborate series of ads we've ever produced." Spanish versions will also be released.

Out and About

Christopher Matthews, who was administrative aide and spokesman for former speaker of the House Tip O'Neill, is moving into the news business as a columnist, radio commentator and newspaper bureau chief. Matthews, who since O'Neill's retirement has been president of Government Research Corp., has signed a contract with King Features to write two political columns a week. In addition, Matthews, who is credited by many as the man most responsible for establishing the speaker's image as the center of opposition to the Reagan administration, will become Washington bureau chief of the San Francisco Examiner. He has also signed a contract with Mutual Radio as a regular political commentator for the 1988 presidential primaries, convention and campaign ...

The gloomy, drizzly skies seemed somehow perfectly suited for the somber little service yesterday at the Jefferson Memorial. It was the 956th day of captivity for Terry Anderson, the Associated Press' Beirut chief taken hostage there in early 1985. It was also his 40th birthday, and the No Greater Love Foundation organized the ceremony to mark the occasion. Among those at the umbrella-covered gathering were Anderson's sister and chief advocate, Peggy Say, and former national security office secretary Fawn Hall ...

Royal Watch: The rumors persist about the apparent chill in Charles and Diana's fairy-tale marriage. Now, however, there is some concern that the press speculation may actually destroy the monarchy. Harold Brooks-Baker, editor of Burke's Peerage, the prestige directory of British nobility, says the country is close to a constitutional crisis. "The press barons do not seem to care at all about the fabric of monarchy," he said in an interview with the British news service Reuter. "The monarchy is very fragile. If the public turned against the monarchy and decided that because of what they read in the papers they did not want the queen any more, she would disappear overnight." Since the queen is one of the richest individuals in the world, there is the consolation that she can disappear in comfort ...