This is not the first time Steve Jobs, had took a leave from Apple. First time being in 2004, Jobs had left Apple because of the fact he was treated for a rare yet dangerous tumor. Later in 2009 while he was in Switzerland, he was yet again taken off because he was being treated for cancer. Steve Jobs had also gone  through a liver transplant back few years ago.

Jobs leaving Apple leaves, Tim Cook in command. We will have to wait and see what happens while he is gone.. will it be the end for Apple? Maybe, maybe not.. Jobs didn't leave a date saying when he will be back, but he did end up leaving a small message for all the workers. January 2011 and Jobs leaving isn't the start Apple wanted.. hopefully it will be better soon enough. 

Here was the message which he had left:

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.