The number of people with the real ability to contend for the overall lead is very small, especially now since the sprinters have fallen behind so far in the mountain stages (many of them openly didn’t care and only rode hard enough not to get disqualified).
As of today, the overal standings at the top are:
1 Lance Armstrong (USA) Discovery Channel
2 Ivan Basso (Ita) Team CSC 2.46
3 Michael Rasmussen (Den) Rabobank 3.46
4 Jan Ullrich (Ger) T-Mobile Team 5.58
5 Francisco Mancebo (Spa) Illes Balears-Caisse d’Epargne 7.08
6 Levi Leipheimer (USA) Gerolsteiner 8.12
7 Cadel Evans (Aus) Davitamon-Lotto 9.49
8 Alexandre Vinokourov (Kaz) T-Mobile Team 10.11
9 Floyd Landis (USA) Phonak Hearing Systems 10.42
These are the people to watch. Everyone in the race knows who these people are, and if any of them go for a breakaway, Discovery will make sure to either pull the peleton (big group) up to the leaders, or jump a couple people and pull just Lance to the leaders. That last bit wouldn’t probably be possible, as there would be a cascade effect of 4-5 other teams trying to pull their stars to the leaders, which would be so many people going that the peleton would just draft behind the huge group going, and you’re back to the whole peleton pumping hard all together, again.
The reason the other stars probably won’t even really try much is that Lance is known as not only a very good climber, but probably the best time trial rider. On the relatively flat stages, getting away from him and his very respectable team is almost impossible.