This video from youtube is simply fantastic. It features the Red Bull F1 team.
Using animated illustrations, it vividly demonstrates the exterior changes to the bodywork of the F1 cars: overall size changes, barge board revisions, front suspension and wing, and rear wing. It also explains the new energy recovery system very well. And yes, slick tires are back for 2009.
After all the chatter over the off season, this is one of the best explanations I have seen. Check it out for yourself: http://www.youtube.com/watch?v=zTkVKPdyWs0
The first Formula One race is now about a month away! Can't wait!