Steve Jobs taking another medical leave, COO Tim Cook in charge

Almost two years to the day after Steve Jobs took a six-month medical leave from the company, the Apple CEO has requested — and was granted — another leave of absence from Apple's board of directors. Jobs will stay on as CEO, but will give Tim Cook, chief operations officer at Apple, the reins in terms of "day-to-day" operations.

The startling news hit the wire Monday morning, a day before Apple's quarterly earnings call, with the company issuing a statement with an e-mail from Jobs to Apple employees:

Team,
At my request, the board of directors has granted me a medical leave of absence so I can focus on my health. I will continue as CEO and be involved in major strategic decisions for the company.
I have asked Tim Cook to be responsible for all of Apple's day to day operations. I have great confidence that Tim and the rest of the executive management team will do a terrific job executing the exciting plans we have in place for 2011.
I love Apple so much and hope to be back as soon as I can. In the meantime, my family and I would deeply appreciate respect for our privacy.
Steve

It wasn't immediately clear what prompted Jobs to take another medical leave, with Apple issuing no details as to the CEO's condition.

That said, it's obviously no secret that the 55-year-old Jobs has looked frail—sometimes alarmingly so—in the past few years, with the Apple co-founder taking an earlier leave of absence back in January 2009, leaving Cook in charge.

That medical leave ended up lasting six months, with Jobs returning to work in June 2009 after undergoing a successful liver transplant. Jobs had already had surgery for pancreatic cancer back in August 2004, with Cook again minding the store during Jobs' month-long recovery.

Unlike the last time Jobs announced he would take medical leave, Monday's announcement didn't give a timeline for when Jobs might return.

All eyes—and ears—will undoubtedly be on Apple's upcoming quarterly earnings call, slated for 5 p.m. ET Tuesday, when analysts and investors are sure to pepper Apple execs with questions about Jobs' health.

The last time Jobs made a major public appearance was back in October, when he took the stage in San Francisco for a preview of Mac OS X "Lion" and to unveil Apple's revamped MacBook Air.

Many had wondered if Jobs might make the trek to New York for last week's announcement of the iPhone finally coming to Verizon. Instead, Apple COO Cook, who's now in charge of day-to-day operations in Cupertino, was dispatched to do the honors.

Jobs' absence didn't raise too many eyebrows at the time, since Verizon's new iPhone is little more than the current iPhone 4 retooled for the carrier's CDMA network, rather than a brand-new device warranting the full Steve Jobs treatment. The event was also hosted by Verizon, not Apple, which had tempered expectations of Jobs making a cameo.

Jobs had also been expected at an event in San Francisco to help take the wraps off News Corp.'s coming iPad newspaper, dubbed "The Daily," as early as this week. But the event was reportedly delayed, ostensibly so Apple and News Corp. could "work out some kinks" in setting up a digital subscription service through iTunes.

Correction: In my original post, I wrote that Monday's announcement marked Steve Jobs' second official medical leave from Apple; in fact, it's his third, including a month-long leave in 2004 following his treatment for pancreatic cancer. Apologies for the error.

— Ben Patterson is a technology writer for Yahoo! News.

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