He looks like a man who has advancing cancer. My dad looked exactly like this when he was getting quite sick. The whole forgetful thing was the same as well.
He looked absolutely terrible yesterday, and I was worried when I saw the Macworld Keynote and the NYC opening interview. He didn't look so bad at the Cupertino City Council meeting.
I wonder if he's actually going to work full time any more. Whatever it is, you can bet that his doctors have been watching him like a hawk.
I'm no doctor, but the only other thing I can think of is that the operation a couple of years back has damaged his pancreas. I had a friend who came down with type 1 diabetes and he looked a lot like Jobs does now until they got his insulin under control.
If he really is sick, and it's not treatable, I wouldn't expect to hear anything from Apple until they are ready. Otherwise, I would expect some sort of denial. In that respect I imagine Apple will treat his case much like the Cuban government is treating Castro's illness.