Perhaps the prospect of a Smothers Brothers anniversary show doesn't sound all that delightful, but the program itself is. It's all that delightful and more: It's sweet. Sweet revenge.

"The Smothers Brothers Comedy Hour 20th Reunion," at 10 tonight on Channel 9, returns the boys to the CBS television network from which they were spinelessly fired in 1969. Well before "Miami Vice" and "Moonlighting" and even "Saturday Night Live," the bros tried to tailor a mainstream network show to a youthful audience, and to give it a distinctive snap. The CBS-TV president, Robert Wood, one of many myopic jellyfish to have held that job, canceled the show for its topical humor and needlings of Lyndon Johnson's Vietnam policy.

The boys were right, the network was wrong; it was clear then, and it's clear now. But time and the dictates of commerce heal wounds. On their special tonight, the brothers tweak CBS only in joshing, good-natured ways.

Tommy uses the word "condom" in a joke, as has now become fairly common, and Dick barks, "It's comments like that that got us kicked off the air in the first place!" The soupcon of political humor on the show comes mostly from withered old reliable Pat Paulsen, who in yet another bid for the presidency observes, "George Bush is kind of like Jerry Ford without the pizazz."

What was forgotten amid the hubbub in 1969 and ought to be remembered now is that, all the so-called controversy aside, the brothers and their team put on a bright and inventive variety show. For the reunion, they have decided to do just that again, with little additional commemorative adornment.

Their act hasn't changed. But it didn't need to. Even in tuxes with bright red bow ties, Tom and Dick are still an engaging pair of neighborhood brats, and each has a recognizable Everybrother side that is timeless. All us guys should be able to act so boyish at their ages and get away with it.

Among the regulars from the old series who return for a visit tonight are Leigh French as Goldie, the flower child (still flashing the peace sign -- remember that?) and Glen Campbell and John Hartford, offering a too-brief reprise of perhaps the best country song ever, "Gentle on My Mind."

The most conspicuous disappointment is comic and actor Steve Martin, a writer for the brothers in the '60s, and clearly too self-important now to make much of a contribution to this special. He's on and off in minutes and not funny.

Otherwise, though, the Smothers Brothers reunion is a treat and a reassurance. It's a little like finding the bedroom you had as a child still untouched and unchanged and waiting for your return -- or like going up to the office of your college newspaper and finding the old gang still there nursing hangovers and dreaming up editorials protesting the war.

Writers from the "Comedy Hour" take a bow with the brothers at the end; they include Rob Reiner, later a famous Meathead and now a successful movie director. Some from the old troupe have gone on to less than glory, and as for the brothers themselves, their chief source of income now seems to be Magnavox commercials. But they appear unbloodied and anything but bowed.

There aren't many clips from the old show; this isn't that kind of hour. Images of guest stars from the original series do fly by now and then -- everybody from Pete Seeger to Kate Smith, from Arthur Godfrey to Jim Morrison. One may feel a sentimental twinge not just for this variety show, but for all variety shows, the genre having become nearly extinct in the interim.

Surely a pure compilation show, of taped highlights from the past, is in order, both as a time capsule exercise and as an edifying entertainment. Of all the moments from the series, the one I remember best, oddly or not, is Jack E. Leonard, the fat insult comedian, singing "The Fool on the Hill" by Lennon and McCartney against a background showing faces of famous clowns. It was a novel idea and it worked.

Or at least it came so close to working that you had to sit back and admire it. Television you can sit back and admire is even rarer now than when the Smothers Brothers were in their prime. Maybe they still are in their prime and it's television that has passed its.