GC guys stand a chance of winning but a lot will depend on how many times the break stays away on the MTFs. Points system is below (mountain with a MTF is doubled.
HC 1 2 3 4
1st 20 10 5 2 1
2nd 16 8 3 1
3rd 12 6 2
4th 8 4 1
5th 4 2
6th 2 1
from (
http://inrng.com/2011/06/tour-de-france-points-kom-competition-newrules/)
Given the average size of a breakaway then GC guys may get very few points before the last mountain. Consider, stage 14.
http://www.letour.fr/2011/TDF/COURSE/us/1400/etape_par_etape.html
Someone from a breakaway, lets say Moncoutie, leads over every climb before the last one, getting himself 32 points. However, if the break is then caught and Contador wins with the other main contenders catching Moncoutie as well then the score stands at Contador 40, Moncoutie 32. Not great news from a KoM point of view for a days attacking. However, if Moncoutie stays away to take a famous victory then he takes 72 points from the stage with fourth place Contador taking just 16. I think someone from a break can win it, they've just got to make sure they get in one that stays away to a MTF and are then able to pick up some other points.
Not sure about Moncoutie, he has done well in the Vuelta but struggled in the Tour and Giro.
Would have thought that one of the RadioShackers could be a good value bet for this - they should have three to count for the team comp if the break does get caught and assuming they dont challenge for the highest spots in the overall then it might be worth having a punt at this too.
EDIT: Problem is that they probably wont be far behind, at least not on the first Pyrenean stage so wont be allowed much time advantage. Maybe later in the race they will have more of a chance unless someone decides to deliberately lose time on the stage to Luz Ardiden or something.