If you are ever in any of France's 27 wine regions during September try to see a Vendanges (grape harvest) in action. It is a slice of French culture that is not seen everyday by most tourists. I have been on my brother-in-law's domain in Burgundy, Domaine de l'Echelette a few times during a Vendanges and it is very interesting to see how wine is made. One time I even got to pick grapes myself, what back breaking work!
Here is a step by step photo essay of the grape harvest process.
Video of grapes being made into sparkling wine in Burgundy.
Video of grapes being picked in Burgundy.
Time Lapse photography of grapes being picked.
Remember the Vendanges is the most important time for a Domaine or Châteaux, so be respectful, stay out of the way and keep your distance when taking photos. That said I would still try to see a Vendanges if possible. So next time you are driving in France and its September remember to keep your eyes open for those funny looking tall tractors that are used to harvest grapes. You could even help out and pick some!