I'm sure we all know this already but the horcrux locket is in the Black House. J.K gave us a very good hint about it in the 5th book.
Here's an excerpt:
There was a musical box that emitted a faintly sinister, tinkling tune when would that they all found themselves becoming curiously weak and sleepy until Ginny had the sense to slam the lid shut; also a heavy locket that none of them could open, a number of ancient seals and, in a dusty box, an Order of Merlin, First Class, that had been awarded to Sirius’s grandfather for “Services to the Ministry.a heavy locket that none of them could open
this just doesn't make sense. if u remember in the books V could not penetrate harry because he was full of love the stuff vold detests. he could not posess harry with out suffering mortal agony. i don't think he could have put a part of his soul into him with out feeling pain.
i also think he would have known full well where he put his soul so i don't think the theory of harry being an accidental horcrux really makes sense. There was a special spell to do it, slughorn told vold that when he asked him he said he didn't know. Otherwise his parts of soul could have been accidentally put in to random things by mistake with out him knowing.
ok i think harry is a horcrux, i thought about this as soon as i finished book 6 and i think he is a horcrux because if voldemort wanted to kill harry he could have just avada kedavra'd his ass but he didnt. It also says voldemort was weak after attemping to "kill" harry this is because he has just given harry a seventh of his soul......think about it.
i think it makes perfect sense for voldemort to have put a part of his soul in harry. think about it... harry is prophecised to be the one to kil the DL but if part of the DL is in him, then without killing himself he cannot completely kill the DL, even if harry were to kill the physical being of voldemort, his soul (or part of it) would still remain in harry.