Forza Motorsport 3 has a video featuring footage from the Le Mans Circuit De La Sarthe. It's after the break.
CVG has loads of screens for the game too. You may have seen some already, though.
There is also a list of cars that have been confirmed for the game over on the site as well.
Again, some of these you may already know about, but it's about cars. Fast cars - and that's cool.