What is your theory about Professor Snape--is he really a traitor?

Dumbledore knows that Snape must maintain his status as a spy for the Deatheaters in order to defeat them. Either he realized that his life was less important than that of the rest of the world, or else he and Snape had a previous arrangement in which Snape would put a curse on Dumbledore to make him appear dead. If I remember correctly, Harry did not see Dumbledore die because he fell over the edge of the building. Also, at the funeral ceremony, Dumbledore's body was consumed (I think it was burned, but it has been a while). The prevalent theme of the Phoenix comes to mind when I think about this, and it makes me think that Dumbledore will be "reborn" in book seven.

I have a feeling Snape is okay. I just don't think Dumbledore would have kept telling Harry to trust him if he weren't. On the other hand, the twists and surprises in the series are what keeps the books so exciting so I guess I would expect anything at this point.

I'm hoping that we'll find out in the next book that Snape really was good all along.

Personally, I think Snape will end up not being evil. It IS possible to be a rotten person, but still fight for what is right. Just because Snape used to be a Death Eater doesn't mean he still is. But I think it is pretty obvious at this point that Snape will play a major role in the next book. Practically the whole story hangs on whether he's good or evil. But right now it's still Rowling's decision. She can work it either way. Sometimes I think she hasn't even decided yet, and writes it in-between until she makes up her mind.

Just one final thing: J.K. Rowling has a masterful way of convincing you something is true when it isn't. So therefore if we think Snape is evil, then by her style, he isn't.

I believe there is more to Prof. Snape that meets the eye. I don't believe that Dumbledore is asking Snape to kill him, I don't believe that Dumbledore wanted to die. I think Snape was protecting Malfoy and was fulfilling the Unbreakable Vow that he made to Malfoy's mother. I believe Snape truly cares for Malfoy and didn't want him to be killed because, despite Malfoy's cruel behavior towards Harry, he is still a child and was threatened by Lord Voldemort that if Malfoy didn't kill Dumbledore that he would kill Malfoy and his family. This is just a theory.

everyone is saying no, so i'll say yes. he killed dumbledore. but regardless of the amount of pain albus was in, he was doomed from the beginning since at the beginning of the book, snape makes an unbreakable vow to kill dumbledore if malfoy can't. it takes someone who is truly evil to do that. after everything dumbledore had done for snape, he agreed to kill him without knowing what was to come next and he had hatred in his eyes when he did it. he was too close to the malfoys and his rivalry with james and siruis was to predomanent for him to be a good guy. i don't think harry will take revenge, though. voldermort will. if snape had heard all of the prophecy like a good spy, voldy may have gone after nevelle, who by then, had no one but his old granny to protect him. when voldermort figures that out, snape will have hell to pay.

I'm hoping its some kind of cover. Dumbledore was always so sure he could trust Snape, and if Sirius Black does not reappear somehow Im going to be really pissed.

I ABSOLUTELY believe that Snape is NOT evil. I agree with everyone that you don't have to be a "good" person to be on the right side of a battle to fight for what you know to be right.

It appears J.K. Rowling has done that thing where she sets up the guy to look evil but at the end he'll be good. If you look at what he's done, there's always the possibility he'll end up good.

He's still a bitter mean man, irregardless of how he helps or works against Voldemort.