The announcement last month, that Apple chief Steve Jobs would not attend or address Macworld 2009 this week in San Francisco, sparked rumours that he was planning to ease into retirement. Later, other rumours started circulating in the Apple fan community that Jobs was seriously ill — perhaps dieing. Now Apple’s official line is that Jobs is, indeed, ill, but not all that seriously.

In a personal letter to Apple employees yesterday, Jobs said, “As many of you know, I have been losing weight throughout 2008. The reason has been a mystery to me and my doctors. A few weeks ago, I decided that getting to the root cause of this and reversing it needed to become my #1 priority. …Fortunately, after further testing, my doctors think they have found the cause—a hormone imbalance that has been ‘robbing’ me of the proteins my body needs to be healthy. Sophisticated blood tests have confirmed this diagnosis.”

Jobs also said that the problem was ‘dietary’ in nature and that he had already started treatment for it.

Some observers say Jobs, who is notoriously secretive about his personal life, elected to come clean about his health issues after serious concerns were voiced in the financial community about Apple’s stability is he was, in fact on the way out.

Jobs’ health issues are not directly connected to Apple’s decision to get out of the trade show game. Late last year, Apple announced this would be its last year at Macworld and other trade and consumer shows, saying it will concentrate instead on its network of Apple Stores and its Apple.com Web site, which allow the company to, “directly reach more than a hundred million customers around the world in innovative new ways.”

Apple’s Senior Vice-President of Worldwide Marketing, Philip Schiller, will speak at today’s Macworld Keynote event. The show runs through this coming Friday at the Moscone Center in San Francisco.