Why is it, folks, that we all want to see Snape as a man caught in a horrible situation?
I'm really curious about that. I've admitted it before, I'll say it again: It's all because of Alan Rickman. He's to blame!
And another thing...when could VM have turned HP into a horcrux? I just don't see it.
I think they are going for when Voldy tried to kill Harry he inadvertantly turned him into a horcrux. I don't see it either. That would mean if Harry were a horcrux that he would have to kill himself or be killed to get rid of Voldy. I just don't see JKR killing off the hero of the series. It would be such a let down.
The theory, such as it is, is that VM transferred part of his soul into Harry at the same time he transferred certain if his powers into Harry (e.g., the ability to speak Parseltongue). That is, at the same time he failed to kill Harry. He'd already killed Harry's parents, so the requisite murdering had already been done. The horcrux could very well be Harry's scar. (Supposedly the last word in Book 7 is "scar." Perhaps the offending sentence will read something like, "for the first time in his life, it was just a scar.")
There is a very short scene in Order of the Phoenix that may support the theory -- where Dumbledore consults one of his odd instruments. Two snakes appear and intertwine, and Dumbledore says something to the effect of "but in essence divided."