Every beer that is brewed at Jolly Pumpkin is aged in oak barrels. One difference with the Leelanau Beers is that they only are aged in new French oak. Meaning that the barrels were custom made of the highest quality oak known to man, generally this type of oak is reserved for only the world's finest wines. The new part simply refers to that the barrels have never been used for anything other than the Leelanau beers, not that the barrels are only used once.
Jolly Pumpkin is famous for open fermentation and wild yeasts- true farmhouse ales.