This post and it's replies contains SPOILERS for "Deathly Hallows".
SNAPE'S PORTRAIT
As we know, after a Headmaster/Headmistress dies, a portrait of them is somehow generated and appears in the Headmaster's office. Harry returns to the office to talk to Dumbledore, but no mention of Snape's portrait is made. Is it not there? If it's not, what could that mean?
My feeling is a portrait of Snape would not be put in the Headmaster's office because of the conditions of Snape's promotion to the position. He was not elected by the Board of Trustees (or whatever), therefore Hogwarts may not recognize him as a rightful Headmaster, even though he was following Dumbledore's orders. And I do think the Hogwarts castle is a kind of living thing, it has an intelligence independent of those who live in it.
Discuss, debate.