Matt Smith is... (spoiler)

[Graham Kennedy]

...the last Doctor.

The story stated a Time Lord can only regenerate twelve times, and Moffat considers the Doctor is now in his thirteenth and final body. John Hurt is now officially a Doctor, sitting between the Eighth and Ninth Doctors, and David Tennant used up an extra regeneration during his stay. The writer was clear about the future, and how the Doctor is now at the end of his cycle - something that could cause problems when Matt Smith turns into Peter Capaldi in the 2013 Christmas episode.

So it's confirmed that as well as Hurt, they are counting the Doctor's partial regeneration in Journey's End, which turned his severed hand into a new Human version of the Doctor. Thus Matt Smith is in fact the 13th Doctor :

1 - Hartnell
2 - Troughton
3 - Pertwee
4 - T. Baker
5 - Davison
6 - C. Baker
7 - McCoy
8 - McGann
9 - Hurt
10 - Eccleston
11 - Tennant
12 - Tennant as the regenerated hand
13 - Smith

And so the Christmas special is going to have to not only give us a new Doctor, but overcome the 12 regeneration limit once and for all.

[RK_Striker_JK_5]

One more reason for me to not like Journey's End...

This should be interesting.

[Captain Seafort]

Called it

[Graham Kennedy]

I'm wondering what they could do about the limit. I think it will be a shame if they just technobabble it away... "Oh, in shutting down that runaway reactor I've been exposed to vertonium energy! It's recharged my regeneration nodules and now I have ten more lives!" Ugh.

We do know, on the other hand, that the timelords could give new regenerations to people, or take them away. Interesting thought, now that Gallifrey is potentially back in play...

[Nutso]

I'm wondering what they could do about the limit. I think it will be a shame if they just technobabble it away... "Oh, in shutting down that runaway reactor I've been exposed to vertonium energy! It's recharged my regeneration nodules and now I have ten more lives!" Ugh.

We do know, on the other hand, that the timelords could give new regenerations to people, or take them away. Interesting thought, now that Gallifrey is potentially back in play...

Whoa. THat would be a really quick resolution to the Gallifrey story if they revived Gallifrey in the Christmas Special.

[Graham Kennedy]

It would. I've been thinking they would play it out over seasons, but who knows. They might surprise us.

[Nutso]

I keep thinking that the answer would be related back to McGann's Doctor dying then being brought back to life. But that would be too obvious, would it not?

[DarkMoineau]

...the last Doctor.

The story stated a Time Lord can only regenerate twelve times, and Moffat considers the Doctor is now in his thirteenth and final body. John Hurt is now officially a Doctor, sitting between the Eighth and Ninth Doctors, and David Tennant used up an extra regeneration during his stay. The writer was clear about the future, and how the Doctor is now at the end of his cycle - something that could cause problems when Matt Smith turns into Peter Capaldi in the 2013 Christmas episode.

So it's confirmed that as well as Hurt, they are counting the Doctor's partial regeneration in Journey's End, which turned his severed hand into a new Human version of the Doctor. Thus Matt Smith is in fact the 13th Doctor :

1 - Hartnell
2 - Troughton
3 - Pertwee
4 - T. Baker
5 - Davison
6 - C. Baker
7 - McCoy
8 - McGann
9 - Hurt
10 - Eccleston
11 - Tennant
12 - Tennant as the regenerated hand
13 - Smith

And so the Christmas special is going to have to not only give us a new Doctor, but overcome the 12 regeneration limit once and for all.

In others interview, Moffat said Hurt was the War Doctor and must not be counted because that's a regenration made by sisters potions.

But I have a problem with your 12: if Tennant regenerated he wouldn't have died. So how to count it as a regenration? For me it look more like he begin to transform into Smith at this moment but delayed it as long as possible.

[IanKennedy]

He's not saying that Tennant's doctor was regenerated. He's saying that that regeneration did happen and resulted in the "human doctor" that went back to the alternate universe with Rose. So the list would read:

11 - Tennant*
12 - Tennant as a human in an alternative universe with Rose*
13 - Smith

* These two reincarnations exist simultaneously, or at least until the 'human' version dies of old age.

[IanKennedy]

Personally, I'm kinda hoping that they don't count that and that Smith is 12. This would mean that Capaldi would be 13 and then go one for a whole long time, eventually finding the Timelords / Gallifrey resulting in him being granted unlimited (or at least another 13) regenerations as the saviour of the race.

[Graham Kennedy]

In others interview, Moffat said Hurt was the War Doctor and must not be counted because that's a regenration made by sisters potions.

I think you have misunderstood. They have said they are not counting Hurt, but only in terms of the official numbering of the Doctors. Meaning they are still going to call Ecclestone "The Ninth Doctor" even though he is actually the tenth. It's purely so they don't confuse everyone by changing what they've been calling the Doctors for the last few years. It doesn't mean they're not actually counting Hurt as one of the Doctor's lives.

But I have a problem with your 12: if Tennant regenerated he wouldn't have died. So how to count it as a regenration? For me it look more like he begin to transform into Smith at this moment but delayed it as long as possible.

Not sure what you mean. IIRC Tennant was zapped and dying, and he started to regenerate. But he let the regeneration go just enough to heal the damage, then channelled the remaining energy into the hand so it didn't rebuild his body. Instead it rebuilt the hand to make the copy which went to live with Rose.

So we were left with the same Doctor... but he'd used up a regeneration.

Here's the dialogue from Journey's End :

DOCTOR (sitting up) : "You see? Used the regeneration energy to heal myself, but soon as I was done, I didn't need to change. I didn't want to, why would I? (he adjust his tie with a smug expression) Look at me! So, to stop the energy going all the way, I siphoned off the rest into a handy bio-matching receptacle, namely, my hand, my hand there, my handy spare hand!"

And...

NEW DOCTOR : "No no no no no, I'm unique. Never been another like me. Cos all that regeneration energy went into the hand. Look at my hand! I love that hand! But then you touched it, WHAM! (Donna jumps and yells) Ssh! Instantaneous biological metacrisis. I grew... (taken aback) out of you! Still, could be worse."

See? One regeneration used up.