Cook also gets a bigger paycheck than any other Apple executive - including Jobs, a multibillionaire and a dollar-a-year-man in terms of salary. Cook's salary, though peanuts compared to his stock grants, is $700,000, about $100,000 more than that of CFO Peter Oppenheimer and retail chief Ron Johnson. And when the company doles out restricted stock, Cook gets the biggest pile; in September that came to 200,000 shares, a bigger grant than anyone else at Apple got.
Jobs has seen to it that Cook is getting public exposure, especially on Wall Street. He is a fixture on Apple's quarterly earnings calls, and he speaks at select investment conferences. "Operationally, when you think about what they've done - a massive retail-stores ramp, an expanded sales-channel presence, delivering new products without glitches, and managing huge seasonality - all speak to a company that is exceedingly well run," says Sacconaghi, the Sanford Bernstein analyst, referring almost wholly to aspects of the company that Cook oversees.
For all that, it isn't difficult to imagine Cook being passed over, especially by someone Jobs might deem to be more in his own mold. Two executives whose stature has risen because of their close association with Jobs' pet areas of focus are design chief Jonathan Ive, 41, and Johnson, 50, the ex-Target executive who runs the retail stores.
Ive, for example, made an appearance in a company video about the manufacturing of Apple's new notebook computers, a signal dissected in the same manner Kremlinologists once used to analyze the placement of Politburo officials at May Day parades. Johnson, because he comes from outside the computer industry, already had a high pre-Apple profile, and he is closely associated with the stunning success of the stores. Neither man, though, has Cook's breadth of responsibility, nor have they demonstrated his combination of business and technical acumen.
A third powerful Apple executive is Oppenheimer, the chief financial officer and a 12-year veteran of the company. Important though Oppenheimer is, most Apple watchers consider it even less likely that a finance executive would head Apple than an operations wonk.
It's notable that Apple's newest senior executive, iPod hardware head Mark Papermaster, reports to Jobs, not Cook. Papermaster, who is 47 and spent 26 years at IBM, may someday emerge as a candidate for the top job. (He replaced Tony Fadell, who recently resigned but remains an advisor to Jobs.)
One astute observer of the board believes it's possible for Jobs to become chairman one day, with Cook as CEO. (Apple's board currently has no chairman. Rather, it has two co-lead directors, Intuit chairman Bill Campbell and Genentech CEO Art Levinson.)
Apple isn't the only company in Silicon Valley without a publicly identified heir apparent. HP's (HPQ, Fortune 500) Mark Hurd hasn't announced a successor, nor have Oracle's (ORCL, Fortune 500) Larry Ellison or Intel's Paul Otellini. But none of those CEOs is the global brand that Jobs is. The guessing game puts Jobs in a quandary. He hates sharing the spotlight, yet he obviously detests the constant speculation about his health - chatter intensified by the lack of transparency about who would replace him.
There's also the question of whether Cook even wants to be CEO - such a high-profile job would attract the kind of public scrutiny he has carefully avoided - or if he'd accept a job elsewhere if one were offered. People who know Cook say he professes a genuine love for Apple. "To me the company is about putting together pieces of the puzzle," Cook told someone recently, "not about getting personal visibility."
As long as Jobs stays healthy, Cook won't need to worry about personal visibility. He can just keep doing his thing, grinding away offstage. But if he does get tapped for the CEO job someday, Apple may not suffer from acute Stevelessness as much as the world seems to think.
Reporter associate Doris Burke contributed to this article. 
