Apple chief executive Steve Jobs is back at work following a near six-month medical leave, although he will work at least initially from home for a few days a week.

The official word of his return followed months of speculation about the health of Jobs, a pancreatic cancer survivor who co-founded Apple more than 30 years ago.

Jobs, 54, underwent a liver transplant in Memphis, Tennessee, while on leave. He has remained involved in strategic decisions at Apple while he’s been away, according to the company, and he has been seen in recent weeks at Apple’s headquarters in Cupertino, California.

“Steve is back to work,” a company spokesman says. “He’s currently at Apple a few days a week and working from home the remaining days. We are very glad to have him back.”

Collins Stewart analyst Ashok Kumar says investors will be reassured that Jobs is back at the helm of the company he helped resuscitate over the past decade, with category-defining products such as the iPod and the iPhone.

Kumar notes that some investors had feared Jobs would never return. “In many ways he’s irreplaceable,” he claims. “Having him back brings the halo back to the company.”

Jobs was treated for a rare form of pancreatic cancer in 2004. His gaunt appearance at an Apple event last summer spurred worries the cancer had returned.

In January, after initially blaming his noticeable weight loss on a hormone imbalance, Jobs announced he was taking medical leave until the end of June, saying his health-related issues were “more complex” than originally thought.

While Jobs was on leave, chief operating officer Tim Cook handled Apple’s day-to-day operations. Some analysts think Jobs may transition into an advisory role, focusing on products and strategy and Cook will formally become CEO.

The hospital in Memphis that performed Jobs’ liver transplant said he “is now recovering well and has an excellent prognosis,” but has not provided further details.

Pacific Crest Securities analyst Andy Hargreaves says questions remain and claims that Apple has not shown itself to be very forthcoming on the subject of Jobs’ health.

“The question is whether or not he’s going to be there for the next several years and I don’t think they’ve added any clarity on that,” he says.

Reuters