Amazing that so many people knew, and no one leaked it... Most famous people who died suddenly of an illness like that (e.g. Freddie Mercury, Bill Hicks) kept it secret except to a circle of close friends. Presumably, hundreds or even thousands knew about this illness, yet not one of them peeped about it.
Of course, it would have been an incredible lack of decorum to do so, and that's probably what stopped them. And yet, it seems fitting that news of Steve's rapidly declining health were even more leak-proof than the average Apple product release.
My girlfriend's father died of the same illness as Jobs. When she saw Jobs giving a keynote in June, she was amazed that he was still working when it was so obvious (to her, having watched her father fade away) that the end was near.
Of course, it would have been an incredible lack of decorum to do so, and that's probably what stopped them. And yet, it seems fitting that news of Steve's rapidly declining health were even more leak-proof than the average Apple product release.