I have borrowed this from a few websites, but the main source is Thomas' excellent velowire blog.
We know a good bit about the first few stages, as Valve Pithy mentions in Post 41 in this topic:
1. Utrecht (ITT)
2. Utrecht - Zeeland (flat, exposed finish)
3. (Antwerp?) - Antwerp (flat)
4. Antwerp - Mur de Huy (flat + hilly finale / uphill finish)
5. Seraing - (France)
Stage 3 as outlined above by Valve Pithy may be dropped. It seems that the first week will have that ITT, Mur de Huy and possibly a TTT as the main difficulties in the first 6 days.
Then the first Saturday (stage 8) seems certain to have the Mur de Bretagne.
The newspapers keep talking about a TTT on the first Sunday, but this is against UCI regulations. Nevertheless, the stage seems to be from Vannes to Plumelec.
All in all a very uninspiring first week, I think. But the rest of the rumoured route looks very good.
Remember the day after the rest day is Bastille Day. And it seems almost certain that this will be celebrated with a stage finish in Arrete La Pierre Saint Martin.
The second Pyreneen stage is likely to be something like Pau to Cauterets.
The third Pyrneen stage goes east, with a finish in Plateau de Beille.
Friday (stage 13) sees a transition flat stage from Castres to Rodez.
Saturday (stage 14) sees a finish in Mende
Sunday (stage 15) is unclear, there had been rumours of a hilly stage in the Ardeche, but nothing concrete.
Monday (stage 16) sees another transition towards the Alps.
Rest on the Tuesday.
Then Wednesday (stage 17) sees a potentially epic Pra Loup finish, taking in Col des Champs and Col de la Cayolle.
The last few days are up in the air. It seems certain there will be a finish in La Toussuire and one in L'Alpe d'Huez. And probably another one in Saint Jean de Maurienne. But other than that it is not clear what the plans are. There may be a time trial somewhere, but the rumours of the Alps are unclear.
So it looks like:
* 3 Pyrneen stages. At least 2 MTF, with the middle stage either Cauterets or a descent.
* 3-4 Alpine stages. At least 2 MTF, with a descent finish likely.
* Short ITT in the first stage, possible TTT in the first week, surely an ITT in the last week, but unclear where it will be. Maybe the Ardeche stage can be an ITT?
* Uphill finish in Huy, Uphill finish in Mur de Bretagne, Uphill finish in Mende.
All those stages look very good, but the key is what they do with the other 9-10 stages. We need some difficulty like cobbles or something in the first week in particular.