He may have taken most of his former White House colleagues by surprise when word got around that Hamilton Jordan was going to challenge Sen. Mack Mattingly for his seat, but nearly 50 of them met with him and his wife Dorothy Wednesday night to offer their support. "He's an underdog in the Georgia Senate race, but he thinks he has a good shot for it," one of his former coworkers said yesterday. Jordan told the group he had been fairly successful since leaving the White House, where he had been former president Jimmy Carter's chief of staff, but that none of the experiences were as satisfying as public service.

"They were all surprised by my decision," Jordan said yesterday. "They had all become accustomed to thinking of me as sick." He said he will finish what he terms successful cancer treatments in January and will eventually make an announcement he is in the race. Jordan said many of those at Wednesday's meeting will be called on to help. At the end of the evening, some had given him checks and others said they would begin working on position papers. Asked if Carter would campaign for him, Jordan said he didn't think anyone was elected by someone else campaigning for him. "I'm going to have to get out there and do it for myself."

Among the friends and associates at the meeting, held in former White House aide Tom Beard's office, were John White, former head of the Democratic National Committee, and old-time Carter-Mondale aides such as Al Eisele, Dick Moe, Si Lazarus, Gail Harrison, Gerald Rafshoon, Tom Donilon, Bob Beckel and Mike Cardozo. A Short Course in Beauty

And you always thought those Miss America beauties were budding brainy rocket scientists. Well, not all of them. The Miss America Pageant, which has had a continual series of embarrassments, last year was once again chagrined when Philadelphian Toni Georgiana, 21, qualified for the Miss New Jersey contest by enrolling in a two-week course at Trenton State College. After winning the crown, she admitted she never attended the class and received a failing grade because she was busy preparing for the pageant.

Georgiana didn't qualify as a national contest finalist in the comical annual Atlantic City ritual -- in fact, she injured herself performing an intricate dance step. And now there has been a rule change that will require out-of-state women to actually attend classes at the college in which they enroll. "And we don't mean for two or three days," pageant director Albert Marks Jr. emphasized. That seems little enough since the new rule will not require the out-of-state contestant to pursue a college degree, be a full-time student or even pass the courses. That would be asking too much. End Notes

President Reagan made a routine happy birthday call yesterday morning to Sen. Strom Thurmond and the South Carolina Republican turned the phone call into a lobbying opportunity. Thurmond is concerned that the president might veto what many consider a protectionist textile bill now on Reagan's desk that restricts the foreign imports of textile apparel goods, an important issue in South Carolina. The president listened for some time but would neither confirm nor deny that a veto was pending. Sometimes those public relations calls aren't as easy as they seem . . .

As anyone certainly would expect, Captain Kirk, also known as William Shatner, will be beamed aboard for tonight's Wright Brothers Memorial Dinner at the Page Avjet Hanger at Washington Dulles International Airport. The former commander of "Star Trek's" Starship Enterprise will emcee the dinner, which will feature the space shuttle Enterprise's transfer to the Smithsonian Institution's National Air and Space Museum. Vice President George Bush will be there to preside over the transfer, and parked near the shuttle will be a Grumman Avenger, the type of plane Bush flew and was shot down in during World War II. Among the expected guests are former senator Jennings Randolph, Sens. John Glenn, Jake Garn and John Warner and embattled NASA Administrator James Beggs, who was indicted this week on charges of trying to defraud the government on the development of an ill-fated Army weapon when he was with General Dynamics . . .

The anti-apartheid efforts of Sen. Bill Bradley, Rep. William Gray, Rep. Howard Berman, Rep. Howard Wolpe and D.C. Delegate Walter Fauntroy were honored yesterday in the House Budget Committee Hearing Room by musicians Little Stevie Van Zandt, Herbie Hancock and Darlene Love, who performed on the Sun City album. Proceeds from the album, released about six weeks ago, will go to families of South African political prisoners, educational aid for South African exiles and groups such as Trans-Africa.