About the unanswered question of "who is the half-blood prince?"
An original editorial by Kara
About the unanswered question of "who is the half-blood prince?" I personally think we should all cool our jets for a bit. This is the first actual information JK has given us about Book 6, and more clues are bound to come our way. JK is clever enough to conceal the plot of the book, even from the cleverest of HP sleuths. She has a way of making sure her titles don't give too much away. Before reading Book 2, there was no way any of us could've known about the chamber of secrets. Before reading Book 3, no one could've possibly known it would be Sirius or that he was innocent. Before reading Books 4 and 5, there was no way to know about the significance of the Goblet of Fire or what exactly the Order of the Phoenix was. If in fact JK has mentioned the half blood prince to us previously, its obviously a well-kept secret.
There are possibilities that she has mentioned them before though. For example, James had a large amount of gold passed on to him with no info of how he came to possess so much wealth. It is possible that Voldie could hate Dumbledore the same way he hates Harry, that they are so similar because they are half bloods. Lucius, who was only connected to Bellatrix on the tapestry, also has a lot of gold and a lot of power, which would probably grant him enough respect to not be blasted of the tapestry.
As I have said before, the chances of any of us correctly guessing what is about to come is slim to none. We at least have to wait until more clues are released. She hasn't even finished the book yet, and I'm sure she will tease us with more trivial facts long before any of us can get our hands on a copy.