Yup, the current batch I'm drinking had French oak chips added to it in the primary after 7 days.
I soaked them in whisky for a week, placed them in a hop ball and lowered it into the primary for a week or so before bottling. Others oven-bake them for 20mins or so to santitize.
If i were to do it again, I'd use more oak as the oakiness was barely noticeable. I had read that the oak can easily be overpowering so I erred on the side of caution and used only ~0.5oz (compared to the recommended amounts of 1-2oz depending on whether it's French, American, spirals, chips etc) for 5 gallons.