• by Thom Forbes  @tforbes, August 25, 2011

It was "more a question of when than if," as one webcast commentator put it this morning but still, the news that Steve Jobs has resigned as CEO of Apple is reverberating around the Internet like the massive bombshell it is. Jobs recommended to Apple's board that "we execute our succession plan" and appoint COO Tim Cook, the longtime No. 2 man, to replace him.

"I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple's CEO, I would be the first to let you know," Jobs wrote in a terse letter. "Unfortunately, that day has come. I hereby resign as CEO of Apple. I would like to serve, if the board sees fit, as chairman of the board, director and Apple employee."

The announcement came after the stock market closed yesterday but Apple's (AAPL on NASDAQ and NYSE) shares dropped more than 5% in afterhours trading. Earlier this month, the company was the world's largest company by stock market value for a short period.

"More than those of any other company, Apple's fortunes and products have been closely associated with Jobs, who gives final approval on all major initiatives," writes Joseph Mann in Financial Times. "His health concerns have been nearly as big a driver of stock movements as Apple's rapidly growing profit."

Cook, however, was widely expected to be the heir apparent and generally gets good grades from analysts, as John Paczkowski reports in All Things Digital. 

"While we do not believe that Steve Jobs is replaceable, it is worth noting that Tim Cook is a proven executive who can handle the pressure and knows how to run the inner workings of Apple in Jobs' shadow," Barclays analyst Ben Reitzes writes in a research note.

Daniel Eran Dilger blogs in Apple Insider that the resignation letter "mocks idea that board had no succession plan." Among other speculation, the Wall Street Journal had written last month about rumors that some directors were looking for an outside CEO in the event of Jobs stepping down. Jobs responded in an email at the time, ""I think it's hogwash."

Jobs' drive, technological vision and business acumen aside, he will perhaps be best remembered as a marketing genius who was able to not only launch new products that answered needs that consumers were not previously aware that they harbored (think iPod, iTunes and iPad) but also could charge a premium for now-generic products (laptops and PCs) while just about everybody else battled it out in the pricing trenches.

In his lede, the New York Times' Davis Streitfeld writes that Jobs' "insistent vision that he knew what consumers wanted made Apple one of the world's most valuable and influential companies."

Other encomiums include:

• "You could make the case that Steve has injected so much of his DNA into Apple that Apple will continue," former Apple executive Guy Kawasaki tells Streitfeld. "Or you can make the case that without Steve, Apple will flounder. But you cannot make the case that Apple without Steve Jobs will be better. Hard to conceive of that."

• Josh Bernoff, senior vp-idea development at Forrester Research, blogs in Advertising Age, that Jobs, by his count, "changed the world five times. Five." Counting Pixar, maybe five and a half. And, he says, no one else even comes close.

• Piper Jaffray analyst Gene Munster says, "Probably [Job's] last great achievement as CEO is grooming his team to keep what he's created going," according to Adweek's Ki Mae Heussner. "He's been the single greatest inspiration for technology for the last 30 years. No CEO has ever meant as much to a company since Henry Ford."

• "Steve Jobs is the world's magic man. No compromises," John Sculley, who almost led Apple into the ground after Jobs left for a decade in 1983, writes in an email to the Wall Street Journal.

Jobs continued to turn up at key product launches despite his health problems, points out the Journal's Yukari Iwatani Kane, "including the introduction of the iPad 2 earlier this year, where he was greeted with a sustained standing ovation."

"I think his brilliance has been well-documented, but what gets forgotten is the bravery with which he's confronted his illness," Sony CEO Howard Stringer tells Iwatani Kane. "For him to achieve this much success under these circumstances doubles his legacy."

Ad Age and Creativity pick "The 10 Best Ads to Come out of Steve Jobs' Reign at Apple" but, in a nod to just how bounteous the choices are, point out that "these are by no means definitive."

ZDNet's Larry Dignan gives us a rundown of Apple management's bench strength, from Cook on down -- basically, a bunch of guys mostly in their late 40s and early 50s.

Sam Grobart, the New York Times' personal technology editor, lends some audio commentary to an updated timeline that traces Apple's history and Jobs' impact, including his medical leaves.

"The big thing about Steve Jobs is not his genius or his charisma but his extraordinary risk-taking," biographer Alan Deutschman tells the New York Times. "Apple has been so innovative because Jobs takes major risks, which is rare in corporate America. He doesn't market-test anything. It's all his own judgment and perfectionism and gut."

Reuters's Poornima Gupta and Edwin Chan recall Jobs' speech to the graduates of Stanford in 2005: "Remembering that I'll be dead soon is the most important tool I've ever encountered to help me make the big choices in life," he said. "Because almost everything -- all external expectations, all pride, all fear of embarrassment or failure -- these things just fall away in the face of death, leaving only what is truly important.

"Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart."

When, not if, indeed.