If Harry is not a Horcrux

[Cindy]

No: HPFGUIDX 136467

And finally, getting down to the real question (and a really
interesting one too- I'm surprised more people haven't given up their
thoughts) that you posed in your original post,

>Cindy:
>So what IS it that is so unique and VALUABLE about Harry?

Christina:

Dumbledore does not say that Harry is unique and valuable, he simply
says that Harry is *more* valuable than he is.  I'm in the camp that
thinks that Dumbledore's hand injury would have proved fatal
eventually.  If Dumbledore was already dying, then naturally he would
be less valuable than the young-and-healthy Harry.

Now Cindy again:

At first I was really inclined to believe that Harry's scar was a 
horcrux.  It hurt him so much, he shared Voldemort's feelings and 
impulses like a good little soul would.  However, its just too pat.  
I like the idea that somehow during Voldemort's rebirthing that he 
summoned back a piece of his soul unknowingly, but then, that 
doesn't fit with the excelerated almost non-stop Voldemort/Harry 
connection in OoTP. So!  And I hope I'm not boring people to death 
here...

Dumbledore and Harry are at the entrance of the cave, DD refuses to 
let Harry shed his blood...

pg 560  HBP AE

"You are very kind Harry...But your blood is worth more than mine..."

and



pg 570 HBP AE

"Why can't I drink the potion instead?" asked Harry desperately.

"Because I am much older, much cleverer, and much less valuable," 
said Dumbledore. 

I get what you are saying Christina, that it's possible that 
Dumbledore knew his days were numbered so why risk Harry? Dumbledore 
says what he means, he doesn't play coy and he doesn't flatter for 
flattery's sake and in no way did we get any sense of Dumbledore 
giving up as in "I'm an old man and I've lived my life" even though 
we can see him preparing Harry for such an event. He was asking for 
Snape until the end, and one would presume it was for his skill in 
bringing him out of the effects of the potion--but circumstances 
changed dramatically. 

But I think its more than that--whatever is special about Harry is 
either symbolic or literally concerns his blood--it's what sets 
Harry apart from anyone else taking on Voldemort, including 
Dumbledore. It's more than his desire to revenge his parents, more 
than being capable of forgiveness of evil, more than having physical 
protection in his blood because he no longer has that.  Blood is a 
theme and important to the ending no doubt...mudblood, pureblood, 
halfblood, Harry's blood.  What ever it is, it is something 
Dumbledore does not possess, and that is saying a lot.