just hearing people's different takes on it and their experiences is helpful.
i know our son knows about death already. that's obvious. i think what is always tricky with children is if they understand the permanence of it at a young age.
when we told our son that his uncle was sick, he made a remark like "oh, but he'll get better" and my wife told him that he would not get better. but we don't know if he took that to mean "ok he'll just be sick all the time" vs. that she meant he's going to die. we will have to tell him the latter part eventually, that much we know, and we don't want to wait until it happens because we don't want him to be blindsided. one of his favorite things to do right now is go down to their house (they live 50 mins away), so we don't want him to show up one time and his uncle is just gone w/out him knowing.