Also, keep in mind that there are many races within the race. Some teams don't have a legitimate GC guy. Take Columbia HTC for example. Michael Rogers is a fine rider, but he won't be on the podium. They are competing for stage wins and the Green Jersey. They also have Tony Martin who is a strong rider for the White Jersey.
Other teams like BBox or Skil Shimano are hoping to get a couple of guys into breakaways that survive and win a stage that would normally be taken by a stronger team. That's already happened a couple of times.
What happens to Astana next year will be really interesting. If they play their cards right they could have the top 3 or 4 finishers this year. Lance wants to start his own team, Alberto is talented enough to have his own team (and a rumor is that he will with the help of an F1 guys). Levi and Andreas could be the stars of other teams, too. The lineup in next year's TdF will see some big changes, I think.