JKR has said that Harry was an unintended Horcrux. There wasn't much of a soul left by that time, anyway. Voldemorts soul was so damaged by then that Harry didn't receive a very large chunk. She has said that because of the state of the soul and how it happened (by accident, not by design) it was really an incomplete Horcrux that was left residing in Harry. Just enough to create a bit of havoc and gift Harry with a few unusual skills. And wasn't Harry seeing through Nagini's eyes when he attacked Arthur Weasley? I always wondered how that happened. I just got the impression that a wee bit of a fragmented soul flew into Harry's scar and he retained a few things from Voldemort, but none of it was intended and Voldemort didn't even know about it for a long time.