I think the tour is tough to call.
Klöden has the best attributes in my opinion. He is in the top 3 TT'ers in the race and top 5 or 6 climbers in the race, and he has come close before. Some say he is mentally fragile, and though I cannot disprove it he has finished 2nd and 3rd before.
Vino is still the favourite because its his team. If he is in equal or close enough shape to Klöden in the mountains he will ride for the maillot jaune ahead of him. He is an improved climber and a very good TTist.
I think these two will be strongest, but both probably won't make the podium as one will work for the other.
The other podium places are really a scramble which is too close to call imo. Karpets, Valverde, Sastre, Menchov and Evans seem to be the favourites for it. But I wouldn't rule out Schleck, Moreau, Leipheimer or Contador. Should be fascanating stuff.