Check out this 50K race report from Brian Desmarais, a blogger friend who ran the 50K at Pumpkin Holler.
Brian ran a 5:38, a very respectable time.
Brian has a great blog called BikeRunBeer and upon reading just a page or two, you'll agree that he is a great writer and photographer.
In his report, I am certain I sensed thoughts of a 100K attempt woven in the last lines of his telling. :-)