The news that Washington Post Executive Editor Leonard Downie Jr. gave to his newsroom just a half-hour ago barely qualifies as news at this point. As has been suggested, intimated, reported, and gossiped about for months, Downie is stepping down from his post.

The timeline, however, is something of a shocker: Downie will vacate his post effective Sept. 8, at which time the new executive editor will take over. Downie was to announce to his staff today that Washington Post Publisher Katharine Weymouth would announce his successor “soon.” No telling whether that announcement would come before the 4th of July holiday or after. Conventional wisdom within the newsroom has long held that the changeover would never occur before the fall elections. Downie says that the break between the conventions, which he’ll attend, and the fall campaign provides a convenient time for the transition.

The move, says Downie, “was a mutually agreed thing” between himself and Weymouth. When asked whether his opinions are weighing on the search for a new top editor, Downie replied, “In all things dealing with the present and future of the newsroom, Katharine and I have worked closely together and I’ve enjoyed the relationship.”

Like his predecessor, the legendary executive editor Ben Bradlee, Downie, 66, will move into something of an emeritus position at the paper, with the title of Vice President, At-Large. The position is unpaid, says Downie, but comes with an office and other perks. He’ll keep his assistant of more than 20 years, Patricia O’Shea, who figures among the paper’s most beloved workers.

OK, but what’s he going to do?

A lot, if you take his word for it. First comes his novel, The Rules of the Game, which will be published in January. He’s also got another novel “in mind” and is pondering a nonfiction tome of some sort—probably a memoir about his times at the Post. Teaching and researching, too: Downie says that he wants to explore opportunities in academe. “I will try to do whatever seems feasible and reasonable in a less-than-full-time job of seeing the news media through this transition,” he says. That’s a strange role for someone who’s leaving his job to let a younger leader do the same thing at the Post, but hey.

In his 17 years helming the Post, Downie has hauled in 25 Pulitzer Prizes, an astonishing tally considering that the paper, over more than a century, has a total of 47. Yet when asked what his biggest accomplishment is, Downie goes straight for sort of vanilla-flavor quote that he’s been giving to media reporters for decades: “The newspaper has grown in its content and its relationship with its readers on the Web as well as in print. It is really a leader in accountability journalism,” he says.

Of the Pulitzers, Downie is particularly proud of the three Post projects that won the lofty public-service awards: A series on the D.C. police department’s record of shooting people; a series on the D.C. government’s management of group homes for the mentally retarded; and last year’s series on the treatment of soldiers and Marines at the Walter Reed Army Medical Center. In all three cases, says Downie, the stories brought about change in their respective spheres.

Downie started at the Post 44 years ago yesterday—in other words, long enough to see a lot of things go right and wrong. He looked on, for example, as the paper, under Bradlee, published Janet Cooke‘s fabricated story about a boy living in the District.

Unless something goes terribly wrong over the summer, Downie will take off with a record unblemished by such scandal—a feat more stunning than his Pulitzer count. While the New York Times was sliming itself with scandals and misguided coverage ranging from the Jayson Blair fabrications to the Wen Ho Lee coverage to the John McCain-has-a-close-friend-who’s-a-lobbyist embarrassment, the Post was motoring along with a bulletproof news report, day in, day out.

The biggest embarrassment that I can recall from the Downie years was when the Metro page reported that a 7-year-old girl had driven her unconscious father to the emergency room. In fact, she hadn’t. That happened about 10 years ago.

The critics may say that Downie ran a boring paper fixated on federal wonkdom; that he never quite got Style; that he didn’t innovate on the Web; that his paper wasn’t flashy enough. But try running a newsroom of 800 or 900 journalists for 17 years without bringing shame on the profession. In a profession where it’s so easy to err, that’s a towering achievement.