As I said I've been rereading Harry Potter and the Half Blood Prince. I'm now convinced Dumbeldore knew he was going to die.
(Why yes, I am still hung up on Dumbeldore's death.. but not in a crazy way, I hope.)
Anyway, I came to this conclusion after I read chapter four where Dumbeldore tells Harry, "Firstly, I wish you to keep your Invisibility Cloak with you at all times from this moment onwards. Even within Hogwarts itself. Just in case, you understand me?"
That's all the proof I need because Harry was wearing the cloak when he died. Mystery solved. For me, at least. No, I didn't pick up on this fact when I first read the book. I'm not sure why. Possibly because I read it in 24 hours. (What I said I was about to prove my dorkiness.) Reading it so quickly I'm sure there are things I missed, just as I'm also sure many of internet crazies will continue to argue the point, even argue that he's not really dead. Even though J.K. has said repeatedly that he is.
Now, I have to get back to my book.