There is a fair amount of points availble for the Polka dot jersey, and tis a good breakaway stage, so i expect to see J. Pineau, Moncoutie in a break for that, and for a stage victory I could easily see LL. Sanchez, Ignatiev, A Movistar rider, a FDJ rider (Casar probably).
IF anyone is going to chase to catch the breakaway I imagine sky for EBH, Omega for Gilbert, and depending on how he recovers, Astana for Vino. on 2 seperate occasion I have seen him win the stage after a stage he made an effort to win to be just short or caught just before the line in Grand Tours (06 Vuelta, lost to Valverde, then next stage attack 1 km to go on an uphill sprinters finish and Last year Mende, followed by Revel) Not sure since today was a gigantic effort.
Also maybe Europcar will chase for Voeckler if he doesn't make the break.
Last time they finish in St. Flour (UNless they been there more recently) Virenque won in 2004 from an all day breakaway out for the mountain points.