According to the NYTimes:
Two people who are familiar with Mr. Jobs’s current medical treatment said he was not suffering from a recurrence of cancer, but a condition that was preventing his body from absorbing food. Doctors have also advised him to cut down on stress, which may be making the problem worse, these people said.
Looks like a prescription for R&R. Be on the lookout for a fattening man in a black mock turtleneck in Tahiti.