Quote Originally Posted by Chaoskiddo
By the way I was just wondering if any of you could explain this from when Harry "died" and was at "Kings Cross" before talking to Dumbledore.

He recoiled. He had spotted the thing that was making the noises. It had the form of a small, naked child, curled on the ground, its skin raw and rough, ayed–looking, and it lay shuddering under a seat where it had been left, unwanted, stuffed out of sight, struggling for breath.
He was afraid of it. Small and fragile and wounded though it was, he did not want to approach it. Nevertheless he drew slowly nearer, ready to jump back at any moment. Soon he stood near enough to touch it, yet he could not bring himself to do it. He felt like a coward. He ought to comfort it, but it repulsed him.
“You cannot help.”

Who's the child...Is it there for Dumbledore to tell Harry he cannot help those who have died? (as the child is a dead abandoned baby?)

I'm pretty sure that was the piece of Voldemort's soul that was mixed in with his. I think its a small child to show voldemort's emotional immaturity or something...but i'm pretty sure it represents voldemort's piece of soul.