I am one of the persuasion that Dumbledore is truly dead (don't yell, all that much at least).
I am really into making icons, and I have recently started doing some icons from the movie posters for all of the LOTR films.
We know that JK uses ideas from other great works of fiction, and uses Tolkiens works as well.
In the first book, Gandalf the Grey dies while fighting that monster (forgive me, I have not read the books for too long). He comes back later, and is known to the community as Gandalf the White...
This brings me to my question. What if Dumbledore is like Gandalf and comes back, but forgets his history (yet grows in power) for the seventh book... after a while, he (from people talking to him) realizes that he was this one guy who did this one thing (saying this for the sake of simplicity), and continues to aid Harry? Just a thought.